Piezoelectric mirror device, optical equipment incorporating the same, and piezoelectric mirror device fabrication process

ABSTRACT

A piezoelectric mirror device fabrication process, including: dividing a silicon wafer into a multiplicity of segments, wherein on one surface of said silicon wafer per segment, a pair of lower electrodes, a mirror portion positioned between said lower electrodes and a pair of mirror support portions adapted to join said mirror portion to said lower electrodes are formed of an electrically conductive material having a Young&#39;s modulus of up to 160 GPa and a melting point higher than that of a piezoelectric element to be formed later; stacking the piezoelectric element and an upper electrode on said lower electrodes; removing the silicon wafer in a desired pattern from another surface of said silicon wafer per segment and obtaining a multiplicity of piezoelectric mirror devices; and dicing said multiplicity of piezoelectric mirror devices into individual ones.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of Ser. No. 12/306,608filed Dec. 24, 2008, the entire contents of which are incorporatedherein by reference. Application Ser. No. 12/306,608 is a National Stageof PCT/JP2008/060630 filed Jun. 4, 2008, which claims the benefit ofpriority to each of JP 2007-152399 filed Jun. 8, 2008 and JP 208-105650filed Apr. 15, 2008.

ART FIELD

The present invention relates generally to a mirror device, and morespecifically to a piezoelectric mirror device that uses a piezoelectricelement for driving a mirror portion, optical equipment incorporatingthat piezoelectric mirror device, and a piezoelectric mirror devicefabrication process.

BACKGROUND ART

Designed to drive a mirror surface to change a reflection path taken bylight depending on its angle of rotation, a mirror device has so farbeen used for, e.g., optical equipments harnessing laser such asprinters, copiers, displays, and projectors. The mirror surface of themirror device is driven in an electrostatic drive mode usingelectrostatic force, a piezoelectric drive mode utilizing apiezoelectric element, and an electromagnetic drive mode usingelectromagnetic force (JP(A)'s 2001-13443, 2002-311376 and 2003-15064).

Of prior art mirror devices, a piezoelectric mirror device of thepiezoelectric drive mode has an advantage of being higher in drivingpower than those of other drive modes. For instance, it has beenfabricated by means of an MEMS (Micro-Electro-Mechanical systems), witha mirror portion formed by etching an SOI substrate and a mirror supportportion for that mirror portion in a rotatable manner.

However, a problem with the conventional piezoelectric mirror device isthat the amount of displacement of the mirror portion is limited,because the mirror support portion is made of a silicon layer (Si) ofhigh rigidity (having a Young's modulus of 166 GPa). For the fabricationof the mirror support portion or the like, it is required to make use ofan SOI substrate having a silicon oxide that provides an etchingstopper; that SOI substrate costs much, placing some limitations onfabrication cost reductions.

DISCLOSURE OF THE INVENTION

The present invention has for its object the provision of apiezoelectric mirror device having a mirror portion with an increasedamount of displacement, a fabrication process for the simplifiedfabrication of such a piezoelectric mirror device, and opticalequipments incorporating such a piezoelectric mirror device.

According to one embodiment of the invention, that object isaccomplishable by the provision of a piezoelectric mirror device, whichcomprises a frame portion having a centrally located opening, a pair ofdrive portions that are a multilayer structure of a lower electrode, apiezoelectric element and an upper electrode and located at said frameportion, a mirror portion positioned at said opening, and a pair ofmirror support portions adapted to support said mirror portion rotatablyrelative to said frame portion depending on the operation of said driveportions, wherein said mirror support portions are formed of a materialhaving a Young's modulus of up to 160 GPa, and said frame portionincludes a cutout or thinner portion at a part of a site wherein thereare said drive portions positioned, wherein said cutout or thinnerportion is in contact with said opening.

In another embodiment of the invention, said mirror support portions areformed integrally with the lower electrode constituting a part of saiddrive portions.

In yet another embodiment of the invention, said mirror support portionsare locked at ends to the lower electrode constituting a part of saiddrive portions.

In a further embodiment of the invention, said mirror support portionsare locked at ends to the thinner portion of said frame portion.

In a further embodiment of the invention, said mirror support portionsare formed integrally with the upper electrode constituting a part ofsaid drive portions.

In a further embodiment of the invention, said mirror portion and saidmirror support portions are formed integrally.

In a further embodiment of the invention, said mirror portion has amirror surface formed of a material different from that of said mirrorsupport portions.

In a further embodiment of the invention, said mirror support portionsare located in opposite directions via said mirror portion andcoaxially.

In a further embodiment of the invention, the axial center of saidmirror support portions is off the center of said mirror portion.

A further embodiment of the invention is directed to a piezoelectricmirror device, which comprises an inner frame portion defined by saidframe portion, X-axis mirror support portions defined by said mirrorsupport portions and X-axis drive portions defined by said driveportions, and further comprises an outer frame portion positioned insuch a way as to surround said inner frame portion via the opening, apair of Y-axis drive portions that are a multilayer structure of thelower electrode, the piezoelectric element and the upper electrode andlocated at said outer frame portion, and a pair of Y-axis mirror supportportions adapted to support said inner frame portion rotatably relativeto said outer framer portion depending on operation of said Y-axis driveportions, wherein said Y-axis mirror support portions are formed of amaterial having a Young's modulus of up to 160 GPa, and said outer frameportion includes a cutout or thinner portion at a part of a site wherethere are the Y-axis drive portions positioned, wherein said cutout orthinner portion is in contact with said opening, said X-axis isorthogonal to said Y-axis, and said mirror portion is biaxiallyrotatable and displaceable.

The invention also provides optical equipment, which comprises a lightsource, a projection screen and an optical system adapted to guide lightleaving said light source to said projection screen, wherein saidoptical system includes any one of the piezoelectric mirror devices asrecited above.

Further, the invention provides a piezoelectric mirror devicefabrication process, which comprises:

a step of dividing a silicon wafer into a multiplicity of segments,wherein on one surface of said silicon wafer per segment, a pair oflower electrodes, a mirror portion positioned between said lowerelectrodes and a pair of mirror support portions adapted to join saidmirror portion to said lower electrodes are formed of an electricallyconductive material having a Young's modulus of up to 160 GPa and amelting point higher than that of a piezoelectric element to be formedlater,

a step of stacking the piezoelectric element and an upper electrode onsaid lower electrodes in this order to prepare a pair of drive portionsthat are a multilayer structure of the lower electrodes, thepiezoelectric element and the upper electrode,

a step of removing the silicon wafer in a desired pattern from anothersurface of said silicon wafer per segment to form an opening therebypreparing a frame portion, wherein said mirror portion is rotatablysupported by said mirror support portions at said opening, and at a partof a site of said frame portion where there are said drive portionspositioned, a cutout or thinner portion is formed in contact with saidopening to obtain a multiplicity of piezoelectric mirror devices, and

a step of dicing said multiplicity of piezoelectric mirror devices intoindividual ones.

Further, the invention provides a piezoelectric mirror devicefabrication process, which comprises:

a step of dividing a silicon wafer into a multiplicity of segments,wherein on one surface of said silicon wafer per segment, a pair oflower electrodes, a piezoelectric element on said lower electrodes andan upper electrode are stacked in this order to prepare a pair of driveportions that are a multilayer structure of the lower electrodes, thepiezoelectric element and the upper electrode,

a step of forming a mirror portion positioned between said driveportions and a pair of mirror support portions extending from saidmirror portion toward said drive portions of a material having a Young'smodulus of up to 160 GPa such that said mirror support portions arelocked at ends to the lower electrodes constituting a part of said driveportions,

a step of removing the silicon wafer in a desired pattern from anothersurface of said silicon wafer per segment to form an opening therebypreparing a frame portion, wherein said mirror portion is rotatablysupported by said mirror support portions at said opening, and at a partof a site of said frame portion where there are said drive portionspositioned, a cutout or thinner portion is formed in contact with saidopening to obtain a multiplicity of piezoelectric mirror devices, and

a step of dicing said multiplicity of piezoelectric mirror devices intoindividual ones.

Further, the invention provides a piezoelectric mirror devicefabrication process, which comprises:

a step of dividing a silicon wafer into a multiplicity of segments,wherein on one surface of said silicon wafer per segment, a pair oflower electrodes, a mirror portion positioned between said lowerelectrodes and a pair of mirror support portions extending from saidmirror portion down toward said lower electrodes are formed of anelectrically conductive material having a Young's modulus of up to 160GPa and a melting point higher than that of a piezoelectric element tobe formed later,

a step of stacking the piezoelectric element and an upper electrode onsaid lower electrodes in this order to prepare a pair of drive portionsthat are a multilayer structure of the lower electrodes, thepiezoelectric element and the upper electrode,

a step of removing the silicon wafer in a desired pattern from anothersurface of said silicon wafer per segment to form an opening therebypreparing a frame portion, wherein said mirror portion is rotatablysupported by said mirror support portions at said opening, and at a partof a site of said frame portion where there are said drive portionspositioned, a thinner portion is formed in such a way as to be incontact with said opening and lock ends of said mirror support portionsto obtain a multiplicity of piezoelectric mirror devices, and

a step of dicing said multiplicity of piezoelectric mirror devices intoindividual ones.

Further, the invention provides a piezoelectric mirror devicefabrication process, which comprises:

a step of dividing a silicon wafer into a multiplicity of segments,wherein on one surface of said silicon wafer per segment, a pair oflower electrodes, a piezoelectric element on said lower electrodes andan upper electrodes are stacked together in this order to prepare a pairof drive portions that are a multilayer structure of the lowerelectrodes, the piezoelectric element and the upper electrode,

a step of forming a mirror portion positioned between said driveportions and a pair of mirror support portions extending from saidmirror portion toward said drive portions of a material having a Young'smodulus of up to 160 GPa,

a step of removing the silicon wafer in a desired pattern from anothersurface of said silicon wafer per segment to form an opening therebypreparing a frame portion, wherein said mirror portion is rotatablysupported by said mirror support portions at said opening, and at a partof a site of said frame portion where there are said drive portionspositioned, a thinner portion is formed in such a way as to be incontact with said opening and lock ends of said mirror support portionsto obtain a multiplicity of piezoelectric mirror devices, and

a step of dicing said multiplicity of piezoelectric mirror devices intoindividual ones.

Further, the invention provides a piezoelectric mirror devicefabrication process, which comprises:

a step of dividing a silicon wafer into a multiplicity of segments,wherein on one surface of said silicon wafer per segment, a pair oflower electrodes and a piezoelectric element on said lower electrodesare formed,

a step of forming a resist layer such that a surface of saidpiezoelectric element is exposed and making said resist layer flat, thenforming an upper electrode positioned on said piezoelectric element, amirror portion positioned halfway between said piezoelectric elementsand a pair of mirror support portions adapted to join said mirrorportion to said upper electrode of an electrically conductive materialhaving a Young's modulus of up to 160 GPa to prepare a pair of driveportions that are a multilayer structure of the lower electrodes, thepiezoelectric element and the upper electrode, and then removing saidresist,

a step of removing the silicon wafer in a desired pattern from anothersurface of said silicon wafer per segment to form an opening therebypreparing a frame portion, wherein said mirror portion is rotatablysupported by said mirror support portions at said opening, and at a partof a site of said frame portion where there are said drive portionspositioned, a cutout or thinner portion is formed in contact with saidopening to obtain a multiplicity of piezoelectric mirror devices, and

a step of dicing said multiplicity of piezoelectric mirror devices intoindividual ones.

Such an inventive piezoelectric mirror device has mirror supportportions formed of a material having a Young's modulus of up to 160 GPa,and a frame portion wherein at a part of the site where there are driveportions positioned, there is a cutout or thinner portion provided; soit is more increased than a conventional piezoelectric mirror device inthe amount of displacement of the mirror portion due to thepiezoelectric element so that there can be a widening of the scan rangeof laser light scanners for, e.g., printers, copiers, and projectors.

The inventive fabrication process makes use of silicon wafers ordispenses with the use of SOI wafers having a silicon oxide layer,contributing more to fabrication cost reductions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of one embodiment of the inventive piezoelectricmirror device.

FIG. 2 is a sectional view of the piezoelectric mirror device shown inFIG. 1, as taken on arrowed line I-I.

FIG. 3 is illustrative of the frame portion of the piezoelectric mirrordevice shown in FIG. 1.

FIG. 4 is a plan view of another embodiment of the inventivepiezoelectric mirror device.

FIG. 5 is a sectional view of the piezoelectric mirror device shown inFIG. 4, as taken on arrowed line II-II.

FIG. 6 is illustrative of the frame portion of the piezoelectric mirrordevice shown in FIG. 4.

FIG. 7 is a plan view of yet another embodiment of the inventivepiezoelectric mirror device.

FIG. 8 is a sectional view of the piezoelectric mirror device shown inFIG. 7, as taken on arrowed line III-III.

FIG. 9 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 10 is a sectional view of the piezoelectric mirror device shown inFIG. 9, as taken on arrowed line IV-IV.

FIG. 11 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 12 is a sectional view of the piezoelectric mirror device shown inFIG. 11, as taken on arrowed line V-V.

FIG. 13 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 14 is a sectional view of the piezoelectric mirror device shown inFIG. 13, as taken on arrowed line VI-VI.

FIG. 15 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 16 is a sectional view of the piezoelectric mirror device shown inFIG. 15, as taken on arrowed line VII-VII.

FIG. 17 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 18 is a sectional view of the piezoelectric mirror device shown inFIG. 17: FIG. 18A is a sectional view as taken on arrowed lineVIII-VIII, and FIG. 18B is a sectional view as taken on arrowed lineIX-IX.

FIG. 19 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 20 is a sectional view of the piezoelectric mirror device shown inFIG. 19: FIG. 20A is a sectional view as taken on arrowed line X-X, andFIG. 20B is a sectional view as taken on arrowed line XI-XI.

FIG. 21 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 22 is a sectional view of the piezoelectric mirror device shown inFIG. 21, as taken on arrowed line XII-XII.

FIG. 23 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 24 is a sectional view of the piezoelectric mirror device shown inFIG. 23, as taken on arrowed line XIII-XIII.

FIG. 25 is a plan view of a further embodiment of the inventivepiezoelectric mirror device.

FIG. 26 is a sectional view of the piezoelectric mirror device shown inFIG. 25: FIG. 26A is a sectional view as taken on arrowed line XIV-XIV,FIG. 26B is a sectional view as taken on arrowed line XV-XV, and FIG.26C is a sectional view as taken on arrowed line XVI-XVI.

FIG. 27 is illustrative of the lower electrodes of the piezoelectricmirror device shown in FIG. 25.

FIG. 28 is illustrative of the piezoelectric element of thepiezoelectric mirror device shown in FIG. 25.

FIG. 29 is illustrative of the upper electrode of the piezoelectricmirror device shown in FIG. 25: FIG. 29A is a plan view, and FIG. 29B isan enlarged sectional view of a site surrounded by a chain line in FIG.29A.

FIGS. 30A to 30E are step diagrams illustrative of one embodiment of thepiezoelectric mirror device fabrication process according to theinvention.

FIGS. 31A to 31C are step diagrams illustrative of one embodiment of thepiezoelectric mirror device fabrication process according to theinvention.

FIGS. 32A to 32D are step diagrams illustrative of another embodiment ofthe piezoelectric mirror device fabrication process according to theinvention.

FIGS. 33A to 33B are step diagrams illustrative of yet anotherembodiment of the piezoelectric mirror device fabrication processaccording to the invention.

FIGS. 34A to 34C are step diagrams illustrative of a further embodimentof the piezoelectric mirror device fabrication process according to theinvention.

FIGS. 35A to 35B are step diagrams illustrative of a further embodimentof the piezoelectric mirror device fabrication process according to theinvention.

FIGS. 36A to 36C are step diagrams illustrative of a further embodimentof the piezoelectric mirror device fabrication process according to theinvention.

FIGS. 37A to 37E are step diagrams illustrative of a further embodimentof the piezoelectric mirror device fabrication process according to theinvention.

FIGS. 38A to 38C are step diagrams illustrative of a further embodimentof the piezoelectric mirror device fabrication process according to theinvention.

FIG. 39 is illustrative in construction of one embodiment of the opticalequipment according to the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the invention are now explained with reference to theaccompanying drawings.

[Piezoelectric Mirror Device]

(1) FIG. 1 is a plan view of one embodiment of the inventivepiezoelectric mirror device, and FIG. 2 is a sectional view of thepiezoelectric mirror device shown in FIG. 1, as taken on arrowed lineI-I. Referring to FIGS. 1 and 2, a piezoelectric mirror device 11 of theinvention comprises a frame portion 12 having a centrally locatedopening 13, a mirror portion 14 positioned at the opening 13, a pair ofmirror support portions 15 adapted to support the mirror portion 14rotatably relative to the frame portion 12, and a pair of drive portions16 that are a multilayer structure of a lower electrode 17, apiezoelectric element 18 and an upper electrode 19 and located at theframe portion 12. And in the invention, the mirror support portions 15are made of a material having a Young's modulus of up to 160 GPa,preferably 30 to 150 GPa, and more preferably 60 to 130 GPa. The frameportion 12 includes a cutout 13 a at a part of the site where there arethe drive portions 16 positioned, and that cutout 13 a is in contactwith the opening 13. It is not preferable that the Young's modulus ofthe mirror support portions 15 exceeds 160 GPa, because the rigidity ofthe mirror support portions 15 grows high; so the amount of displacementof the mirror portion 14 due to the driving portions 16 grows small.

It is here noted that the lower electrode 17 is connected to a terminal17 b via a wire 17 a, and that the upper electrode 19 is connected to aterminal 19 b via a wire 19 a.

The frame member 12 forming a part of the piezoelectric mirror device 11is made of silicon, and may have any desired thickness optionallyselected from the range of about 300 μm to 1 mm.

The opening 13 formed in the frame 12 defines a space in which themirror portion 14 supported by a pair of mirror support portions 15 ispositioned, and the mirror portion 14 is rotated by the drive portions16 relative to the frame portion 12. Although such opening 13 isconfigured into a rectangle as shown, it is understood that there is nospecial limitation on it as long as it is configured and sized in such away as not to interfere with the rotation of the mirror portion 14.

As shown in FIG. 3, the cutout 13 a that the frame portion 12 has isformed in contact with the opening 13. There is no special limitation onthe configuration and size of the cutout 13 a provided that there is nointerference with the displacement of the mirror supports 15 and themirror portion 14 due to the deformation of the drive portions 16. Inthe embodiment shown, the cutout 13 a is almost the same as the driveportions 16 in a widthwise direction (indicated by an arrow a in FIGS. 1and 3), and configured such that a support site 12′ for supporting thedrive portions 16 is left in the frame portion 12 in a lengthwisedirection (indicated by an arrow b in FIGS. 1 and 3). In that case, thearea of the support site 12′ may be set at up to 50%, preferably 10 to30% of the area of projection of the piezoelectric element 18 forming apart of the drive portions 16 in a thickness-wise direction.

In the piezoelectric mirror device 11, the mirror portion 14, the mirrorsupport portions 15 and the lower electrode 17 are formed integrally ofan electrically conductive material having a Young's modulus of up to160 GPa, preferably 30 to 150 GPa, and more preferably 60 to 130 GPa,and the mirror portion 14 may have any desired shape and area. Themirror support portions 15 are located such that they are coaxiallyopposite to each other with the mirror portion 14 interposed betweenthem. Such mirror portion 14 and mirror support portions 15 levitateover the aforesaid opening 13; so to have structural resistance, theymay have any desired thickness T optionally selected from the range ofat least 500 nm, and preferably 1 to 100 μm. The mirror support portions15 may have any desired width W determined in consideration ofstructural resistance and the rotation of the mirror portion 14 andoptionally selected from the range of, e.g., 1 to 50 μm.

Electrically conductive materials having a Young's modulus of up to 160GPa, for instance, include Al (70.3 GPa), Au (78.0 GPa), Ag (82.7 GPa),Cu (130 GPa), Zn (108.0 GPa), and Ti (115.7 GPa), which may be usedalone or in a multilayer structure form comprising two or more. Evenelectrically conductive materials having a Young's modulus of greaterthan 160 GPa, for instance, Pt (168 GPa), Ni (199 GPa), steel (201.0GPa), and Fe (211.4 GPa) may be used in the event that in combinationwith an electrically conductive material(s) having a Young's modulus ofup to 160 GPa, they provide a multilayer structure having a Young'smodulus of up to 160 GPa. Throughout the disclosure here, it isunderstood that the Young's modulus of the multilayer structure isdefined by dividing the sum of the product of the Young's modulus andthickness of each electrically conductive material by the sum of thethickness of each electrically conductive material. For instance, theYoung's modulus of a multilayer structure comprising an electricallyconductive material 1 having a Young's modulus E₁ and a thickness T₁ andan electrically conductive material 2 having a Young's modulus E₂ and athickness T₂ may be figured out from the following equation:

E=[(E ₁ ×T ₁)+(E ₂ ×T ₂)]/(T ₁ +T ₂)

It is here noted that the axial center of the mirror support portions 15is in alignment with the center of the mirror portion 14 in theembodiment shown; however, if the axial center of the mirror supportportions 15 is off the center of the mirror portion 14, it is thenpossible to improve the ability of the mirror portion to rotate a lotmore.

It is also noted that when the light reflectance of the electricallyconductive material used for the mirror portion 14, the mirror supportportions 15, and the lower electrode 17 is insufficient, the mirrorportion 14 may as well have a reflective layer formed of, e.g., Al, Ag,Rh, Au, Cu, Ni or the like.

The piezoelectric element 18 forming a part of the drive portions 16 maybe formed of conventionally known piezoelectric materials such as leadtitanate zirconate (PZT), barium titanate (BTO), lead titanate (PTO),lithium niobate (LiNbO₃), lithium tantalate (LiTaO₃), and lithiumtetraborate (Li₂B₄O₇). The piezoelectric element 18 may have any desiredthickness optionally selected from the range of, e.g., 5 to 100 μm.

The upper electrode 19 forming a part of the drive portions 16 may beformed of Pt, Au, Ag, Pd, Cu, Sn and so on alone or in combination oftwo or more. It may also be formed of a multilayer structure comprisingan underlay metal layer of Cr, Ti, Mo, Ta or the like and a surfacelayer formed of the aforesaid metal(s) and located on the underlay metallayer. The upper electrode 19 may have any desired thickness optionallyselected from the range of, e.g., 300 nm to 5 μm.

FIG. 4 is a plan view of another embodiment of the inventivepiezoelectric mirror device, and FIG. 5 is a sectional view of thepiezoelectric mirror device shown in FIG. 4, as taken on arrowed lineII-II. Referring to FIGS. 4 and 5, a piezoelectric mirror device 11′ ofthe invention is the same as the aforesaid piezoelectric mirror device11 with the exception that of the frame portion 12, a part of the sitewhere there are the drive portions 16 positioned includes a thinnerportion 12 a instead of the aforesaid cutout 13 a. Therefore, like partsare indicated by like numerals; so their explanations are left out.

As shown in FIG. 6, the thinner portion 12 a that the frame 12 has isformed in contact with the opening 13. There is no special limitation onthe configuration and size of that thinner portion 12 a provided thatthere is no interference with the displacement of the mirror supportportions 15 and the mirror portion 14 due to the deformation of thedrive portions 16. In the embodiment shown, the thinner portion 12 a isconfigured such that it is positioned substantially under and all overthe drive portions 16. The thinner portion 12 a may have any desiredthickness optionally selected from the range of e.g., up to 50 μm, andpreferably 1 to 30 μm.

With such piezoelectric mirror device 11, 11′, for instance, theterminal 17 b (lower electrode 17) side is at a GND potential, and asthe desired ac voltage is applied to the upper electrode 19 via theterminal 19 b, it enables the mirror portion 14 to displace at anydesired resonant frequency. And the mirror support portions 15 areformed of a material having a Young's modulus of up to 160 GPa and theframe portion 12 includes the cutout 13 a or thinner portion 12 a at apart of the site where there are the drive portions positioned: thepiezoelectric mirror device 11, 11′ is much larger in the amount ofdisplacement of the mirror portion by the piezoelectric element thanconventional ones.

(2) FIG. 7 is a plan view of yet another embodiment of the inventivepiezoelectric mirror device, and FIG. 8 is a sectional view of thepiezoelectric mirror device shown in FIG. 7, as taken on arrowed lineIII-III.

Referring to FIGS. 7 and 8, a piezoelectric mirror device 21 of theinvention comprises a frame portion 22 having a centrally locatedopening 23, a mirror portion 24 positioned at the opening 23, a pair ofmirror support portions 25 adapted to support the mirror portion 24rotatably relative to the frame portion 22, and a pair of drive portions26 that are a multilayer structure of a lower electrode 27, apiezoelectric element 28 and an upper electrode 29 and located at theframe portion 22. The aforesaid mirror support portion 25 is made of amaterial having a Young's modulus of up to 160 GPa, preferably 30 to 150GPa, and more preferably 60 to 130 GPa. The frame portion 22 includes acutout 23 a at a part of the site where there are the drive portions 26positioned, and that cutout 23 a is in contact with the opening 23. Itis not preferable that the Young's modulus of the mirror supportportions 25 exceeds 160 GPa, because the rigidity of the mirror supportportions 25 grows high; so the amount of displacement of the mirrorportion 24 due to the driving portions 26 grows small.

It is here noted that the lower electrode 27 is connected to a terminal27 b via a wire 27 a, and that the upper electrode 29 is connected to aterminal 29 b via a wire 29 a.

The frame member 22 forming a part of the piezoelectric mirror device 21is the same as the frame portion 12 in the aforesaid embodiment, and theopening 23 and cutout 23 a may be provided as is the case with theaforesaid opening 13 and cutout 13 a.

In the piezoelectric mirror device 21, the mirror portion 24 and themirror support portions 25 are formed integrally of an electricallyconductive material having a Young's modulus of up to 160 GPa,preferably 30 to 150 GPa, and more preferably 60 to 130 GPa, and themirror portion 24 may have any desired shape and area. The mirrorsupport portions 25 are located such that they are coaxially opposite toeach other with the mirror portion 24 interposed between them. The endsof each mirror support portion 25 are locked to the lower electrode 27forming a part of the drive portions 26. Such mirror portion 24 andmirror support portions 25 levitate over the aforesaid opening 23; so tohave structural resistance, they may have any desired thickness Toptionally selected from the range of at least 500 nm, and preferably 1to 100 μm. The mirror support portions 25 may have a width W determinedin consideration of structural resistance and the rotation of the mirrorportion 24 and optionally selected from the range of, e.g., 1 to 50 μm.

For the material having a Young's modulus of up to 160 GPa, there is themention of the electrically conductive materials mentioned in connectionwith the aforesaid embodiment as well as insulating materials such aspolyethylene, polystyrene, and polyimide. Such materials may be usedalone or in a multilayer structure form comprising two or more. Evenmaterials having a Young's modulus of greater than 160 GPa may be usedin the event that in combination with the material(s) having a Young'smodulus of up to 160 GPa, they provide a multilayer structure having aYoung's modulus of up to 160 GPa.

It is here noted that the axial center of the mirror support portions 25is in alignment with the center of the mirror portion 24 in theembodiment shown; however, if the axial center of the mirror supportportions 25 is off the center of the mirror portion 24, it is thenpossible to improve the ability of the mirror portion to rotate a lotmore.

It is also noted that when the light reflectance of the material usedfor the mirror portion 24 and the mirror support portions 25 isinsufficient, the mirror portion 24 may as well have a reflective layerhaving a higher light reflectance. For such a reflective layer, the samematerials as already mentioned may just as well be used.

The lower electrode 27 forming a part of the drive portions 26 extendsmore on the side of the opening 23 than the piezoelectric element 28 orupper electrode 29, and the ends of the mirror support portions 25 arelocked to that extension site. Such lower electrode 27 may be formed ofPt, Au, Ag, Pd, Cu, Sn and so on alone or in combination of two or more.It may also be formed of a multilayer structure comprising an underlaymetal layer of Cr, Ti, Mo, Ta or the like and a surface layer formed ofthe aforesaid metal(s) and located on the underlay metal layer. Thelower electrode 27 may have any desired thickness optionally selectedfrom the range of, e.g., 300 nm to 5 μm.

The piezoelectric element 28 and upper electrode 29 forming the driveportion 26 may be the same as the piezoelectric element 18 and upperelectrode 19 forming the drive portions 16 in the aforesaid embodiment.

FIG. 9 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 10 is a sectional view of thepiezoelectric mirror device shown in FIG. 9, as taken on arrowed lineIV-IV. Referring to FIGS. 9 and 10, a piezoelectric mirror device 21′ ofthe invention is the same as the aforesaid piezoelectric mirror device21 with the exception that of the frame portion 22, a part of the sitewhere there are the drive portions 26 positioned includes a thinnerportion 22 a instead of the aforesaid cutout 23 a, and that thinnerportion 22 a is in contact with the opening 23. Therefore, like partsare indicated by like numerals; so their explanations are left out.

There is no special limitation on the configuration and size of thatthinner portion 22 a that the frame 22 includes, provided that there isno interference with the displacement of the mirror support portions 25and the mirror portion 24 due to the deformation of the drive portions26. In the embodiment shown, the thinner portion 22 a is configured suchthat it is positioned substantially under and all over the driveportions 26. The thinner portion 22 a may have any desired thicknessoptionally selected from the range of e.g., up to 50 μm, and preferably1 to 30 μm.

With such piezoelectric mirror device 21, 21′, for instance, theterminal 27 b (lower electrode 27) side is at a GND potential, and asthe desired ac voltage is applied to the upper electrode 29 via theterminal 29 b, it enables the mirror portion 24 to displace at anydesired resonant frequency. And the mirror support portions 25 areformed of the material having a Young's modulus of up to 160 GPa and theframe portion 22 includes the cutout 23 a or thinner portion 22 a at apart of the site where there are the drive portions 26 positioned: thepiezoelectric mirror device 21, 21′ is much larger in the amount ofdisplacement of the mirror portion due to the piezoelectric element thanconventional ones.

(3) FIG. 11 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 12 is a sectional view of thepiezoelectric mirror device shown in FIG. 11, as taken on arrowed lineV-V. Referring to FIGS. 11 and 12, a piezoelectric mirror device 31 ofthe invention comprises a frame portion 32 having a centrally locatedopening 33, a mirror portion 34 positioned at the opening 33, a pair ofmirror support portions 35 adapted to support the mirror portion 34rotatably relative to the frame portion 32, and a pair of drive portions36 that are a multilayer structure of a lower electrode 37, apiezoelectric element 38 and an upper electrode 39 and located at theframe portion 32. The aforesaid mirror support portions 35 are each madeof a material having a Young's modulus of up to 160 GPa, preferably 30to 150 GPa, and more preferably 60 to 130 GPa. The frame portion 32includes a thinner portion 32 a at a part of the site where there arethe drive portions 36 positioned, and that thinner portion 32 a is incontact with the opening 33. It is not preferable that the Young'smodulus of the mirror support portions 35 exceeds 160 GPa, because therigidity of the mirror support portions 35 grows high; so the amount ofdisplacement of the mirror portion 34 due to the drive portions 36 growssmall.

It is here noted that the lower electrode 37 is connected to a terminal37 b via a wire 37 a, and that the upper electrode 39 is connected to aterminal 39 b via a wire 39 a.

The frame member 32 forming a part of the piezoelectric mirror device 31is formed of silicon, and may have any desired thickness optionallyselected from the range of about 300 μm to 1 mm.

The opening 33 formed in the frame 32 defines a space in which themirror portion 34 supported by a pair of mirror support portions 35 ispositioned, and the mirror portion 34 is rotated by the drive portions36 relative to the frame portion 32. Although such opening 33 isconfigured into a rectangle as shown, it is understood that there is nospecial limitation on it as long as it is configured and sized in such away as not to interfere with the rotation of the mirror portion 34.

There is no special limitation on the configuration and size of thethinner portion 32 a that the frame portion 32 includes, provided thatthere is no interference with the displacement of the mirror supportportions 35 and the mirror portion 34 due to the deformation of thedrive portions 36. In the embodiment shown, the thinner portion 32 a ispositioned almost under the drive portions 36, and extends more on theside of the opening 33 than the drive portions 36, with the ends of themirror support portions 35 locked to that extension site. Such thinnerportion 32 a may have any desired thickness optionally selected from therange of, e.g., up to 50 μm, and preferably 1 to 30 μm.

In the piezoelectric mirror device 31, the mirror portion 34 and themirror support portions 35 are formed integrally of a material having aYoung's modulus of up to 160 GPa, preferably 30 to 150 GPa, and morepreferably 60 to 130 GPa, and the mirror portion 34 may have any desiredshape and area. The mirror support portions 35 are located such thatthey are coaxially opposite to each other with the mirror portion 34interposed between them, and the end of each mirror support portion 35is locked to the thinner portion 32 a of the frame portion 32. Suchmirror portion 34 and mirror support portions 35 levitate over theaforesaid opening 33; so to have structural resistance, they may haveany desired thickness T optionally selected from the range of at least500 nm, and preferably 1 to 100 μm. The mirror support portions 35 mayhave a width W determined in consideration of structural resistance andthe rotation of the mirror portion 34, and optionally selected from therange of, e.g., 1 to 50 μm.

For the material having a Young's modulus of up to 160 GPa, use may bemade of the electrically conductive materials mentioned in connectionwith the aforesaid embodiments as well as the insulating materialsreferred to in the aforesaid embodiments. Such materials may be usedalone or in a multilayer structure form comprising two or more. Evenmaterials having a Young's modulus of greater than 160 GPa may be usedin the event that in combination with the material(s) having a Young'smodulus of up to 160 GPa, they provide a multilayer structure having aYoung's modulus of up to 160 GPa.

It is here noted that the axial center of the mirror support portions 35is in alignment with the center of the mirror portion 34 in theembodiment shown; however, if the axial center of the mirror supportportions 35 is off the center of the mirror portion 34, it is thenpossible to improve the ability of the mirror portion to rotate a lotmore.

It is also noted that when the light reflectance of the material usedfor the mirror portion 34 and the mirror support portions 35 isinsufficient, the mirror portion 34 may as well have a reflective layerhaving a higher light reflectance. For such a reflective layer, the samematerials as already mentioned may just as well be used.

The lower electrode 37, piezoelectric element 38 and upper electrode 39constituting the drive portions 36 may be formed of the same material(s)as in the lower electrode 27, piezoelectric element 28 and upperelectrode 29 constituting the aforesaid drive portions 26.

With such piezoelectric mirror device 31, for instance, the terminal 37b (lower electrode 37) side is at a GND potential, and as the desired acvoltage is applied to the upper electrode 39 via the terminal 39 b, itenables the mirror portion 34 to displace at any desired resonantfrequency. And the mirror support portions 35 are formed of the materialhaving a Young's modulus of up to 160 GPa and the frame portion 32includes the thinner portion 32 a at a part of the site where there arethe drive portions 36 positioned: the piezoelectric mirror device 31 ismuch larger in the amount of displacement of the mirror portion due tothe piezoelectric element than conventional ones.

(4) FIG. 13 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 14 is a sectional view of thepiezoelectric mirror device shown in FIG. 13, as taken on arrowed lineVI-VI. Referring to FIGS. 13 and 14, a piezoelectric mirror device 41 ofthe invention comprises a frame portion 42 having a centrally locatedopening 43, a mirror portion 44 positioned at the opening 43, a pair ofmirror support portions 45 adapted to support the mirror portion 44rotatably relative to the frame portion 42, and a pair of drive portions46 that are a multilayer structure of a lower electrode 47, apiezoelectric element 48 and an upper electrode 49 and located at theframe portion 42. The aforesaid mirror support portions 45 are each madeof a material having a Young's modulus of up to 160 GPa, preferably 30to 150 GPa, and more preferably 60 to 130 GPa. The frame portion 42includes a cutout 43 a at a part of the site where there are the driveportions 46 positioned, and that cutout 43 a is in contact with theopening 43. It is not preferable that the Young's modulus of the mirrorsupport portions 45 exceeds 160 GPa, because the rigidity of the mirrorsupport portions 45 grows high; so the amount of displacement of themirror portion 44 due to the driving portions 46 grows small.

It is here noted that the lower electrode 47 is connected to a terminal47 b via a wire 47 a, and that the upper electrode 49 is connected to aterminal 49 b via a wire 49 a.

The frame member 42 forming a part of the piezoelectric mirror device 41is much the same as the frame portion 12 in the aforesaid embodiments,and the opening 43 and cutout 43 a may be provided as is the case withthe aforesaid opening 13 and cutout 13 a.

In the piezoelectric mirror device 41, the mirror portion 44 and themirror support portions 45 are formed integrally of a material having aYoung's modulus of up to 160 GPa, preferably 30 to 150 GPa, and morepreferably 60 to 130 GPa, and the mirror portion 44 may have any desiredshape and area. The mirror support portions 45 are located such thatthey are coaxially opposite to each other with the mirror portion 44interposed between them. Such mirror portion 44 and mirror supportportions 45 levitate over the aforesaid opening 43; so to havestructural resistance, they may have any desired thickness T selectedfrom the range of at least 500 nm, and preferably 1 to 100 μm. Themirror support portions 45 may have a width W determined inconsideration of structural resistance and the rotation of the mirrorportion 44, and optionally selected from the range of, e.g., 1 to 50 μm.

For the material having a Young's modulus of up to 160 GPa, use may bemade of the electrically conductive materials mentioned in connectionwith the aforesaid embodiments. Such materials may be used alone or in amultilayer structure form comprising two or more. Even materials havinga Young's modulus of greater than 160 GPa may be used in the event thatin combination with the material(s) having a Young's modulus of up to160 GPa, they provide a multilayer structure having a Young's modulus ofup to 160 GPa.

It is here noted that the axial center of the mirror support portions 45is in alignment with the center of the mirror portion 44 in theembodiment shown; however, if the axial center of the mirror supportportions 45 is off the center of the mirror portion 44, it is thenpossible to improve the ability of the mirror portion to rotate a lotmore.

It is also noted that when the light reflectance of the material usedfor the mirror portion 44, the mirror support portions 45, and the upperelectrode 49 is insufficient, the mirror portion 44 may as well have areflective layer having a higher light reflectance. For such areflective layer, the same materials as already mentioned may just aswell be used.

The lower electrode 47, and the piezoelectric element 48 constitutingthe drive portions 46 may be formed of the same material(s) as in thelower electrode 17 and the piezoelectric element 18 constituting theaforesaid drive portions 16 in the aforesaid embodiment.

FIG. 15 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 16 is a sectional view of thepiezoelectric mirror device shown in FIG. 15, as taken on arrowed lineVII-VII. Referring to FIGS. 15 and 16, a piezoelectric mirror device 41′of the invention is the same as the aforesaid piezoelectric mirrordevice 41 with the exception that of the frame portion 42, a part of thesite where there are the drive portions 46 positioned includes a thinnerportion 42 a instead of the cutout 43 a, and that thinner portion 42 ais in contact with the opening 43. Therefore, like parts are indicatedby like numerals; so their explanations are left out.

There is no special limitation on the configuration and size of thatthinner portion 42 a provided that there is no interference with thedisplacement of the mirror support portions 45 and the mirror portion 44due to the deformation of the drive portions 46. In the embodimentshown, the thinner portion 42 a is configured such that it is positionedsubstantially under and all over the drive portions 46. The thinnerportion 42 a may have any desired thickness optionally selected from therange of e.g., up to 50 μm, and preferably 1 to 30 μm.

With such piezoelectric mirror device 41, 41′, for instance, theterminal 47 b (lower electrode 47) side is at a GND potential, and asthe desired ac voltage is applied to the upper electrode 49 via theterminal 49 b, it enables the mirror portion 44 to displace at anydesired resonant frequency. And the mirror support portions 45 areformed of the material having a Young's modulus of up to 160 GPa and theframe portion 42 includes the cutout 43 a or thinner portion 42 a at apart of the site where there are the drive portions 46 positioned: thepiezoelectric mirror device 41, 41′ is much larger in the amount ofdisplacement of the mirror portion due to the piezoelectric element thanconventional ones.

(5) FIG. 17 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 18A is a sectional view of thepiezoelectric mirror device shown in FIG. 17, as taken on arrowed lineVIII-VIII while FIG. 18B is a sectional view of the piezoelectric mirrordevice shown in FIG. 17, as taken on arrowed line IX-IX. Referring toFIGS. 17, 18A and 18B, a piezoelectric mirror device 51 of the inventioncomprises a frame portion 52 having a centrally located opening 53, amirror portion 54 positioned at the opening 53, a pair of mirror supportportions 55 adapted to support the mirror portion 54 rotatably relativeto the frame portion 52, and a pair of drive portions 56 that are amultilayer structure of a lower electrode 57, a piezoelectric element 58and an upper electrode 59 and located at the frame portion 52. And themirror support portions 55 are each made of a material having a Young'smodulus of up to 160 GPa, preferably 30 to 150 GPa, and more preferably60 to 130 GPa. The frame portion 52 includes a cutout 53 a at a part ofthe site where there are the drive portions 56 positioned, and thatcutout 53 a is in contact with the opening 53. It is not preferable thatthe Young's modulus of the mirror support portions 55 exceeds 160 GPa,because the rigidity of the mirror support portions 55 grows high; sothe amount of displacement of the mirror portion 54 due to the drivingportions 56 grows small.

It is here noted that the lower electrode 57 is connected to a terminal57 b via a wire 57 a, and that the upper electrode 59 is connected to aterminal 59 b via a wire 59 a.

Such piezoelectric mirror device 51 is much the same as the aforesaidpiezoelectric mirror device 11 with the exception that the shape of thecutout 53 a that the frame portion 52 has and the shape of the driveportions 56 are different. That is, the piezoelectric mirror device 51has a pair of C-shaped drive portions 56 located in such a way as tosurround the opening 53, and the cutout 53 a, too, is in a C-shapedconfiguration (surrounded with a chain line in FIG. 17).

FIG. 19 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 20A is a sectional view of thepiezoelectric mirror device shown in FIG. 19, as taken on arrowed lineX-X while FIG. 20B is a sectional view of the piezoelectric mirrordevice shown in FIG. 19, as taken on arrowed line XI-XI. Referring toFIGS. 19, 20A and 20B, a piezoelectric mirror device 51′ of theinvention is much the same as the aforesaid piezo-electric mirror device51 with the exception that the frame portion 52 includes, at a part ofthe site where there are the drive portions positioned, a thinnerportion 52 a in place of the cutout 53 a, and that thinner portion 52 ais in contact with the opening 53. Therefore, like parts are indicatedby light references; so their explanations are left out.

The thinner portion 52 a that the frame 52 has is configured such thatit is positioned almost under and all over the drive portions 56, ashatched in FIG. 19. The thinner portion 52 a may have any desiredthickness optionally selected from the range of e.g., up to 50 μm,preferably 1 to 30 μm.

With such piezoelectric mirror device 51, 51′, for instance, theterminal 57 b (lower electrode 57) side is at a GND potential, and asthe desired ac voltage is applied to the upper electrode 59 via theterminal 59 b, it enables the mirror portion 54 to displace at anydesired resonant frequency. And the mirror support portions 55 areformed of the material having a Young's modulus of up to 160 GPa and theframe portion 52 includes the cutout 53 a or thinner portion 52 a at apart of the site where there are the drive portions 56 positioned: thepiezoelectric mirror device 51, 51′ is much larger in the amount ofdisplacement of the mirror portion due to the piezoelectric element thanconventional ones.

It is here noted that in the aforesaid piezoelectric mirror device 21,21′, 31, 41, 41′, too, the drive portions may as well be C-shaped, andthe cutout or thinner portion may as well be C-shaped, but of course,they may have other configurations.

(6) FIG. 21 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 22 is a sectional view of thepiezoelectric mirror device shown in FIG. 21, as taken on arrowed lineXII-XII. Referring to FIGS. 21 and 22, a piezoelectric mirror device 61of the invention comprises a frame portion 62 having a centrally locatedopening 63, a mirror portion 64 positioned at the opening 63, a pair ofmirror support portions 65 adapted to support the mirror portion 64rotatably relative to the frame portion 62, and a pair of drive portions66 that are a multilayer structure of a lower electrode 67, apiezoelectric element 68 and an upper electrode 69 and located at theframe portion 62. And the mirror support portions 65 are each made of amaterial having a Young's modulus of up to 160 GPa, preferably 30 to 150GPa, and more preferably 60 to 130 GPa. The frame portion 62 includes acutout 63 a at a part of the site where there are the drive portions 66positioned, and that cutout 63 a is in contact with the opening 63. Itis not preferable that the Young's modulus of the mirror supportportions 65 exceeds 160 GPa, because the rigidity of the mirror supportportions 65 grows high; so the amount of displacement of the mirrorportion 64 due to the driving portions 66 grows small.

It is here noted that the lower electrode 67 is connected to a terminal67 b via a wire 67 a, and that the upper electrode 69 is connected to aterminal 69 b via a wire 69 a.

Such piezoelectric mirror device 61 is much the same as the aforesaidpiezoelectric mirror device 11 with the exception that the shape of thecutout 63 a that the frame portion 62 has, and the shape of the driveportions 66 is different. That is, the piezoelectric mirror device 61has a pair of drive portions 66 located in such a way as to extend inthe opening 63 so that the displacement of the mirror portion 64 due tothe operation of the drive portions 66 can take place more efficiently.

FIG. 23 is a plan view of a further embodiment of the inventivepiezoelectric mirror device, and FIG. 24 is a sectional view of thepiezoelectric mirror device shown in FIG. 23, as taken on arrowed lineXIII-XIII. Referring to FIGS. 23 and 24, a piezoelectric mirror device61′ of the invention is much the same as the aforesaid piezo-electricmirror device 61 with the exception that the frame portion 62 includes,at a part of the site where there are the drive portions 66 positioned,a thinner portion 62 a in place of the cutout 63 a, and that thinnerportion 62 a is in contact with the opening 63. Therefore, like partsare indicated by light references; so their explanations are left out.

The thinner portion 62 a that the frame 62 has is configured such thatit is positioned almost under and all over the drive portions 66. Thethinner portion 62 a may have any desired thickness optionally selectedfrom the range of e.g., up to 50 μm, preferably 1 to 30 μm.

With such piezoelectric mirror device 61, 61′, for instance, theterminal 67 b (lower electrode 67) side is at a GND potential, and asthe desired ac voltage is applied to the upper electrode 69 via theterminal 69 b, it enables the mirror portion 64 to displace at anydesired resonant frequency. And the mirror support portions 65 areformed of the material having a Young's modulus of up to 160 GPa and theframe portion 62 includes the cutout 63 a or thinner portion 62 a at apart of the site where there are the drive portions 66 positioned: thepiezoelectric mirror device 61, 61′ is much larger in the amount ofdisplacement of the mirror portion by the piezoelectric element thanconventional ones.

It is here noted that in the aforesaid piezoelectric mirror device 21,21′, 31, 41, 41′, too, the cutout or thinner portion of the frameportion may as well be formed such that the drive portions extend intothe opening.

(7) FIG. 25 is a plan view of a further embodiment of the inventivepiezoelectric mirror device; FIG. 26A is a sectional view of thepiezoelectric mirror device shown in FIG. 25, as taken on arrowed lineXIV-XIV; FIG. 26B is a sectional view of that, as taken on arrowed lineXV-XV; and FIG. 26C is a sectional view of that, as taken on arrowedline XVI-XVI. Referring to FIGS. 25, 26A, 26B and 26C, a piezoelectricmirror device 71 of the invention is of the biaxial type that comprisesa frame portion 72 made up of an annular form of inner frame portion 72Ahaving a centrally located inner opening 73A of round shape and an outerframe portion 72B positioned outside the inner frame portion 72A with anannular form of outer opening 73B interposed between them, a mirrorportion 74 positioned at the inner opening 73A, a pair of X-axis mirrorsupport portions 75 adapted to support the mirror portion 74 rotatablyrelative to the inner frame portion 72A, and a pair of X-axis driveportions 76 that are a multilayer structure of a lower electrode 77, apiezoelectric element 78 and an upper electrode 79 and positioned in theinner opening 73A. The X-axis mirror supports 75 are formed integrallywith the lower electrode 77 constituting a part of X-axis drive portions76, and a pair of X-axis drive portions 76 in a semi-annular form areopposite to each other with the X-axis mirror support portions 75interposed between them. Across and over the outer opening 73B there area pair of Y-axis mirror support portions 85 provided that are adapted tosupport the inner frame portion 72A rotatably relative to the outerframe portion 72B, and at the outer opening 73B there are a pair ofY-axis drive portions 86 positioned that are a multilayer structure of alower electrode 87, a piezoelectric element 88 and an upper electrode89. The Y-axis mirror support portions 85 are formed integrally with thelower electrode 87 constituting a part of Y-axis drive portions 86, anda pair of Y-axis drive portions 86 in a semi-annular form are oppositeto each other with the Y-axis mirror support portions 85 interposedbetween them. And the X-axis drive portions 76 a extend from a pair ofsemi-annular X-axis drive portions 76 to the inner frame portion 72A ina direction coaxial to the Y-axis mirror support portions 85, and theY-axis drive portions 86 a extend from a pair of semi-annular Y-axisdrive portions 86 to the outer frame portion 72B in a direction coaxialto the X-axis mirror support portions 75. It is here noted that theaxial direction of the X-axis mirror support portions 75 is set at anangle of 90° with the axial direction of the Y-axis mirror supportportions 85.

And in the invention, the X-axis mirror support portions 75, and theY-axis mirror support portions 85 are each made of a material having aYoung's modulus of up to 160 GPa, preferably 30 to 150 GPa, and morepreferably 60 to 130 GPa. It is not preferable that the Young's modulusof the X-axis mirror support portions 75, and the Y-axis mirror supportportions 85 exceeds 160 GPa, because the rigidity of the respectivemirror support portions grows high; so the amount of displacement of themirror portion 74 due to the X-axis drive portions 76 and the Y-axisdrive portions 86 grows small.

The aforesaid piezoelectric mirror device 71 is now explained in furtherdetails with reference to FIGS. 27, 28 and 29. FIG. 27 illustrates thepiezoelectric mirror device 71 of FIG. 25, where the upper electrodes79, 89 and the piezoelectric elements 78, 88 are removed to expose toview the lower electrodes 77, 87, the X-mirror support portions 75 andthe Y-axis mirror support portions 85, with the mirror portion 74, theX-axis support portions 75, the lower electrodes 77, 87 and the Y-axismirror support portions 85 indicated by hatches; FIG. 28 illustrates thepiezoelectric mirror device 71 of FIG. 25, where the upper electrodes79, 89 are removed to expose the piezoelectric elements 78, 88 to view,with the piezoelectric elements 78, 88 indicated by hatches; FIG. 29Aillustrates the piezoelectric mirror device 71 of FIG. 25 where theupper electrodes 79, 89 are indicated by hatches; and FIG. 29B is anenlarged, sectional view of a site encircled with a chain line in FIG.29A.

As shown in FIG. 27, the annular form of lower electrode 77 ispositioned in the inner opening 73A, and the annular form of lowerelectrode 87 is positioned in the outer opening 73B. Inside the lowerelectrode 77 there is the mirror portion 74 positioned, and a pair ofX-axis mirror supports 75 are located oppositely and coaxially with themirror portion 74 positioned between them for connection to the lowerelectrode 87. And the X-axis mirror support portions 75 extend beyondthe annular lower electrode 77, and have their ends locked to the innerframe portion 72A; the Y-axis mirror support portions 85 extendoppositely and coaxially from the annular lower electrode 87 and havetheir ends locked to the inner and outer frame portions 72A and 72B; andthe lower electrode 77 a extends from the annular lower electrode 77 tothe inner frame portion 72A in such a way as to be coaxial to the Y-axismirror support portions 85. On the other hand, the lower electrode 87 aextends from the annular lower electrode 87 to the outer frame portion72B in coaxial relation to the X-axis mirror support portions 75. Thus,the lower electrodes 77, 77 a, the lower electrodes 87, 87 a, mirrorportion 74, the X-axis mirror support portions 75 and the Y-axis mirrorsupport portions 85 are integrally formed of an electrically conductivematerial having a Young's modulus of up to 160 GPa, preferably 30 to 150GPa, and more preferably 60 to 130 GPa.

For the electrically conductive material having a Young's modulus of upto 160 GPa, use may be made of those mentioned in connection with theaforesaid embodiments. Such materials may be used alone or in amultilayer structure form comprising two or more. Even materials havinga Young's modulus of greater than 160 GPa may be used in the event thatin combination with the material(s) having a Young's modulus of up to160 GPa, they provide a multilayer structure having a Young's modulus ofup to 160 GPa. It is here noted that when the light reflectance of thematerial used is insufficient, the mirror portion 74 may as well have areflective layer having a higher light reflectance. For such areflective layer, the same materials as already mentioned may just aswell be used.

Supporting the mirror portion 74, the X-axis mirror support portions 75must have structural resistance, and supporting the inner frame portion72A, the Y-axis mirror support portions 85 must have structuralresistance. In other words, the X-axis mirror support portions 75 musthave a thickness T1 (see FIG. 26A) selected from the range of at least500 nm, preferably 1 to 100 μm, and the Y-axis mirror support portions85 must have a thickness T2 (see FIG. 26C) selected from the range of atleast 500 nm, preferably 1 to 100 μm. The width W1 of the X-axis mirrorsupport portions 75, and the width W2 of the Y-axis mirror supportportions 85 (see FIG. 27) may optionally be determined in considerationof the ability of the mirror portion 74 or the inner frame portion 72Ato rotate as well as their structural resistance.

It is here noted that a pair of Y-axis mirror support portions 85 inconduction to the lower electrode 87 as already mentioned are eachconnected to a terminal 90 b via a wire 90 a.

As shown in FIG. 28, there are a pair of semi-annular piezoelectricelements 78 located on the lower electrode 77, with the X-axis mirrorsupport portions 75 interposed between them, and the piezoelectricelement 78 a is formed in such a way as to cover the lower electrode 77a from that piezoelectric element 78. On the other hand, a pair ofsemi-annular piezoelectric elements 88 are located on the lowerelectrode 87 in such a way as to be opposite to each other with theY-axis mirror support portions 85 sandwiched between them. Likewise, thepiezoelectric element 88 a is formed in such a way as to cover the lowerelectrode 87 a from that piezoelectric element 88. Such piezoelectricelements 78, 88 may each be formed of conventionally known piezoelectricmaterials such as lead titanate zirconate (PZT), barium titanate (BTO),lead titanate (PTO), lithium niobate (LiNbO₃), lithium tantalate(LiTaO₃), and lithium tetraborate (Li₂B₄O₇). The piezoelectric elements78, 88 may each have any desired thickness optionally selected the rangeof, e.g., 5 to 100 μm.

Further, as shown in FIG. 29A, the upper electrodes 79, 79 a, 89, 89 aare located in such a way as to cover the piezoelectric elements 78, 78a, 88, 88 a, and the upper electrode 79 a that covers the piezoelectricelement 78 a extends to a position where a part of the Y-axis mirrorsupport portions 85 locked to the inner frame portion 72A is coveredwith it, as shown in FIG. 29B. This makes conduction between the Y-axismirror support portions 85 (lower electrode 77) and the upper electrode79. Such upper electrodes 79, 79 a, 89, 89 a may be formed of Pt, Au,Ag, Pd, Cu, Sn and so on alone or in combination of two or more. It mayalso be formed of a multilayer structure comprising an underlay metallayer of Cr, Ti, Mo, Ta or the like and a surface layer formed of theaforesaid metal(s) and located on the underlay metal layer. Such upperelectrodes may have any desired thickness optionally selected from therange of, e.g., 300 nm to 5 μm.

It is noted that the upper electrode 89 a is connected to a terminal 91b via a wire 91 a.

With such piezoelectric mirror device 71 of the biaxial type, forinstance, the lower electrode 77 is at a GND potential, and as thedesired ac voltage is applied from the terminal 90 b to the upperelectrode 79 via the Y-axis mirror support portions 85 and the upperelectrode 79 a, it enables the X-axis drive portions 76 to be driven atany desired resonant frequency thereby displacing the mirror portion 74.The lower electrode 87 is at a GND potential, on the other hand, and asthe desired ac voltage is applied from the terminal 91 b to the upperelectrode 89 via the upper electrode 89 a, it enables the Y-axis driveportions 86 to be driven at any desired resonant frequency therebydisplacing the inner frame portion 72A. And the X-axis mirror supportportions 75 and the Y-axis mirror support portions 85 are formed of thematerial having a Young's modulus of up to 160 GPa and the X- and Y-axisdrive portions 76 and 86 are positioned at the openings (cutouts) 73Aand 73B: the biaxial type piezoelectric mirror device here is muchlarger in the amount of displacement of the mirror portion due to thepiezoelectric elements than conventional ones.

The aforesaid piezoelectric mirror device embodiments are provided forthe purpose of illustration only; the inventive piezoelectric mirrordevice is never limited to them.

[Piezoelectric Mirror Device Fabrication Process]

The fabrication process for the inventive piezoelectric mirror device isnow explained.

(1) FIGS. 30A to 30E and FIGS. 31A to 31C are step diagrams illustrativeof one embodiment of the inventive fabrication process wherein thepiezoelectric mirror device 11, 11′ shown in FIGS. 1 to 6 is taken as anexample.

First of all, a silicon wafer 1 is divided into a multiplicity ofsegments (1A in FIG. 30A), and on one surface of the silicon wafer 1 persegment, a pair of lower electrodes 17, a mirror portion 14 positionedbetween the lower electrodes 17, and a pair of mirror support portions15 adapted to join the mirror portion 14 to the lower electrodes 17 areformed of the electrically conductive material having a Young's modulusof up to 160 GPa (FIGS. 30A and 31A). The electrically conductivematerial having a Young's modulus of up to 160 GPa, for instance,includes Al (70.3 GPa), Au (78.0 GPa), Ag (82.7 GPa), Cu (130 GPa), Zn(108.0 GPa), and Ti (115.7 GPa). To prevent the mirror portion 14, themirror support portions 15 and the lower electrode 17 from meltingduring sintering for the formation of the piezoelectric element 18 at alater step, the electrically conductive material whose melting point ishigher than that of the formed piezoelectric element 18 may beselectively used from the aforesaid electrically conductive materials.Such electrically conductive materials may be used alone or in amultilayer structure form comprising two or more. Even electricallyconductive materials having a Young's modulus of greater than 160 GPa,for instance, Pt (168 GPa), Ni (199 GPa), steel (201.0 GPa), and Fe(211.4 GPa) may be used in the event that in combination with theelectrically conductive material(s) having a Young's modulus of up to160 GPa, they provide a multilayer structure having a Young's modulus ofup to 160 GPa.

The mirror portion 14, the mirror support portions 15 and the lowerelectrodes 17, for instance, may be formed as an integral member byforming the desired resist pattern on the silicon wafer 1, then formingan electrode film by sputtering or the like using the aforesaidelectrically conductive material(s) in such a way as to cover thatresist pattern, and finally removing the resist pattern simultaneouslywith removal (lifting-off) of an unnecessary electrode film portion.Alternatively, they may be formed as an integral member by forming anelectrode film on the silicon wafer 1 by means of sputtering or the likeusing the aforesaid electrically conductive material, then forming thedesired resist pattern on the electrode film, then etching the electrodefilm using that resist pattern as a mask, and finally removing anunnecessary resist pattern portion. Yet alternatively, they may beformed as an integral member by printing on the silicon wafer 1 aphotosensitive, electrically conductive paste containing the aforesaidelectrically conductive material(s), then exposing the electricallyconductive paste to light via the desired mask and developing it, andfinally sintering it.

It is here noted that at this step, the wire 17 a and the terminal 17 b(see FIGS. 1 and 4), too, may be formed at the same time.

Then, the piezoelectric element 18 is formed on the lower electrodes 17(FIGS. 30B and 31B), and the upper electrode 19 is formed on thepiezoelectric element 18 to form a pair of drive portions 16 that are amultilayer structure of the lower electrodes 17, piezoelectric element18 and upper electrode 19 (FIGS. 30C and 31C).

The piezoelectric element 18, for instance, may be formed by providing afilm in the desired pattern by means of sputtering or the like through amask, using a conventionally known piezoelectric material such as leadtitanate zirconate (PZT), barium titanate (BTO), lead titanate (PTO),lithium niobate (LiNbO₃), lithium tantalate (LiTaO₃), and lithiumtetraborate (Li₂B₄O₇), and finally sintering that film. Thepiezoelectric element 18 formed may have any desired thicknessoptionally selected from the range of, e.g., 5 to 100 μm.

The upper electrode 19 may be formed of Pt, Au, Ag, Pd, Cu, Sn or thelike alone or a combination of two or more. It may have a multilayerstructure wherein a surface layer formed of the aforesaid metal(s) isstacked on an underlay metal layer of Cr, Ti, Mo, Ta or the like. Theupper electrode 19 may be formed in the same manner as the aforesaidupper electrode 17 is formed, and has any desired thickness optionallyselected from the range of, e.g., 300 nm to 5 μm. At this process step,the wire 19 a and the terminal 19 b (FIGS. 1 and 4), too, may be formedat the same time.

It is noted that when the light reflectance of the electricallyconductive material used for the mirror portion 14, the mirror supportportions 15 and the lower electrodes 17 is insufficient, a reflectivelayer comprising a high reflectance material such as Al, Ag, Rh, Au, Cu,and Ni should better be formed on the mirror portion 14 after thecompletion of formation of the piezoelectric element 18 (sinteringstep).

Then, the desired site of the silicon wafer 1 is taken out of anothersurface of the silicon wafer 1 to form the opening 13, thereby providingthe frame portion 12. In that case, the cutout 13 a is formed in a partof the site where there are the drive portions 16 positioned, such thatit is in contact with the opening 13, thereby preparing a multiplicityof piezoelectric mirror devices 11 (FIG. 30D). Alternatively, instead ofthe cutout 13 a, the thinner portion 12 a is formed at a part of thesite where there are the drive portions 16 positioned, such that it isin contact with the opening 13, thereby preparing a multiplicity ofpiezoelectric mirror devices 11′ (FIG. 30E).

For instance, the opening 13 and the cutout 13 a may be formed in thesilicon wafer 1 by forming a resist pattern having openingscorresponding to the opening 13 and cutout 13 a on another surface ofthe silicon wafer 1 (free of the mirror portion 14, mirror supportportions 15 and drive portions 16), and implementing DRIE (deep reactiveion etching) using that resist pattern as a mask.

In that case, at the site where there are the lower electrodes 17, thatlower electrodes 17 act as an etching stopper so that the cutout 13 a isformed, and at another site, a through-hole is formed through thesilicon wafer 1 to form the opening 13.

For the formation of the opening 13 and the thinner portion 12 a in thesilicon wafer 1, for instance, a resist pattern for the formation of theopening 13 is first formed on another surface of the silicon wafer 1(free of the mirror portion 14, mirror support portions 15 and driveportions 16), and DRIE (deep reactive ion etching) using that resistpattern as a mask is then implemented down to a depth corresponding tothe thickness of the thinner portion 12 a. Thereafter, the aforesaidresist pattern is removed to form a resist pattern having openingscorresponding to the opening 13 and thinner portion 12 a. Finally, DRIEusing that resist pattern as a mask is implemented until there is athrough-hole formed, thereby forming the opening 13 and thinner portion12 a.

Then, a multiplicity of piezoelectric mirror devices 11 are diced intosuch individual piezoelectric mirror devices 11 as shown in FIGS. 1, 2and 3. Likewise, a multiplicity of piezoelectric mirror devices 11′ arediced into such individual piezoelectric mirror devices 11′ as shown inFIGS. 4, 5 and 6.

It is appreciated that such piezoelectric mirror devices 51, 51′ asshown in FIGS. 17 to 20, and such piezoelectric mirror devices 61, 61′as shown in FIGS. 21 to 24 may just as well be fabricated by theaforesaid inventive fabrication process.

Such piezoelectric mirror device 71 as shown in FIGS. 25 to 29, too, maybe formed by the aforesaid inventive fabrication process. In this case,on the silicon wafer 1 there are the mirror portion 74, the X-axismirror support portions 75, the lower electrodes 77, 87 and the Y-axismirror support portions 85 formed in the order shown in FIGS. 27, 28 and29. Then, the piezoelectric elements 78, 88 are formed, followed by theformation of the upper electrodes 79, 89. Thereafter, the silicon wafer1 is etched to form the inner opening 73A and the outer opening 73B, anddicing is implemented, yielding individual piezoelectric mirror devices71.

(2) FIGS. 32A to 32D and FIGS. 33A and 33B are step diagrams for anotherembodiment of the inventive fabrication process where the piezoelectricmirror device 21, 21′ shown in FIGS. 7 to 10 is taken as an example.

First of all, a silicon wafer 1 is divided into a multiplicity ofsegments (indicated by 1A in FIG. 32A). Then, on one surface of thesilicon wafer 1 per segment, a pair of lower electrodes 27 are providedper segment, and an piezoelectric element 28 and an upper electrode 29are stacked on the lower electrodes 27 in this order to prepare a pairof drive portions 26 that are a multilayer structure of lower electrodes27, piezoelectric element 28 and upper electrode 29 (FIGS. 32A and 33A).The lower electrodes 27 forming a part of a pair of drive portions 26extend mutually toward another pair of drive portions 26 so as to lockmirror support portions 25 there at a later step.

The lower electrodes 27 may each be formed of Pt, Au, Ag, Pd, Cu, Sn orthe like alone or in combination of two or more. Alternatively, it mayhave a multilayer structure wherein a surface layer formed of theaforesaid metal(s) is formed on an underlay metal layer of Cr, Ti, Mo,Ta or the like. The lower electrodes 27 may be formed as is the casewith the lower electrodes 17 in the aforesaid embodiment, and may haveany desired thickness optionally selected from the range of, e.g., 300nm to 5 μm.

The piezoelectric element 28 may be formed as is the case with thepiezoelectric element 18 in the aforesaid embodiment, and may have anydesired thickness optionally selected from the range of, e.g., 5 to 100μm.

Likewise, the upper electrode 29 may be formed as is the case with theupper electrode 19 in the aforesaid embodiment, and may have any desiredthickness optionally selected from the range of, e.g., 300 nm to 5 μm.

It is here noted that the wire 27 a and terminal 27 b as well as thewire 29 a and terminal 29 b (see FIGS. 7 and 9), too, may be formed atthe same time.

Then, a mirror portion 24 and a pair of mirror support portions 25adapted to join the mirror portion 24 to the lower electrodes 27 areformed of the material having a Young's modulus of up to 160 GPa suchthat they are positioned between a pair of drive portions 26 (FIGS. 32Band 33B). For the material having a Young's modulus of up to 160 GPa,just only the electrically conductive materials mentioned in theaforesaid embodiment but also insulating materials such as polyethylene,polystyrene, and polyimide may be used. Such materials may be used aloneor in combination of two or more providing a multilayer structure.Further, even materials having a Young's modulus of greater than 160 GPamay be used in the event that in combination with the electricallyconductive material(s) having a Young's modulus of up to 160 GPa, theyprovide a multilayer structure having a Young's modulus of up to 160GPa. It is here noted that the piezoelectric element 28 has been formedat the previous step; there is no special need of taking care of themelting point of the material used with a Young's modulus of up to 160GPa.

The mirror portion 24 and mirror support portions 25 may be formed as isthe case with the mirror portion 14 and mirror support portions 15 inthe aforesaid embodiment. However, it is noted that the mirror supportportions 25 are formed such that their ends are locked to the extensionsof the lower electrodes 27 forming a part of the drive portions 26.

It is noted that when the light reflectance of the electricallyconductive material used for the mirror portion 24 and the mirrorsupport portions 25 is insufficient, a reflective layer comprising ahigh reflectance material should better be formed on the mirror portion24. Such a reflective layer may be formed of the same materials asmentioned in the aforesaid embodiment.

Then, the desired site is removed from another surface of the siliconwafer 1 per segment to form an opening 23, thereby forming a frameportion 22. Here, if the cutout 23 a is formed in a part of the sitewhere there are the drive portions 26 positioned, such that it is incontact with the opening 23, a multiplicity of piezoelectric mirrordevices 21 are then prepared (FIG. 32C), and if the thinner portion 22 ais formed at a part of the site where there are the drive portions 26positioned, such that it is in contact with the opening 23, amultiplicity of piezoelectric mirror devices 21′ are then prepared (FIG.32D).

The formation of the opening 23 and cutout 23 a in the silicon wafer 1,and the formation of the opening 23 and thinner portion 22 a in thesilicon wafer 1 may be implemented as is the case with the formation ofthe opening 13 and cutout 13 a, and the opening 13 and thinner portion12 a in the aforesaid embodiment.

Then, a multiplicity of piezoelectric mirror devices 21 are diced intosuch individual piezoelectric mirror devices 21 as shown in FIGS. 7 and8. Likewise, a multiplicity of piezoelectric mirror devices 21′ arediced into such individual piezoelectric mirror devices 21′ as shown inFIGS. 9 and 10.

(3) FIGS. 34A to 34C and FIGS. 35A and 35B are step diagrams for yetanother embodiment of the inventive fabrication process where thepiezoelectric mirror device 31 shown in FIGS. 11 and 12 is taken as anexample.

First of all, a silicon wafer 1 is divided into a multiplicity ofsegments (indicated by 1A in FIG. 33A). Then, on one surface of thesilicon wafer 1 per segment, a pair of lower electrodes 37, a mirrorportion 34 positioned between the lower electrodes 37, and a pair ofmirror support portions 35 adapted to support the mirror portion 34 areeach formed of the material having a Young's modulus of up to 160 GPa(FIGS. 34A and 35A). The lower electrodes 37, mirror portion 34 andmirror support portion 35 may be formed as is the case with the lowerelectrodes 17, mirror portion 14 and mirror support portions 15 in theaforesaid embodiment. However, the mirror support portions 35 are formedsuch that their ends provide positions where they are lockable to thethinner portion 32 a formed later. The material used with a Young'smodulus of up to 160 GPa has a melting point higher than that of thepiezoelectric element 38 formed later, thereby ensuring that the mirrorportion 34, mirror support portions 35 and lower electrodes 37 do notmelt during sintering for the later formation of the piezoelectricelement 38.

It is here noted that at this step, a wire 37 a and a terminal 37 b (seeFIG. 11) may be formed at the same time, too, and that when the lightreflectance of the electrically conductive material used for the mirrorportion 34 and the mirror support portions 35 is insufficient, areflective layer comprising a high reflectance material should better beformed on the mirror portion 34. Such a reflective layer may be formedof the same materials as mentioned in the aforesaid embodiment.

Then, the piezoelectric element 38 and upper electrode 39 are formed onthe lower electrodes 37 to form a pair of drive portions 36 that are amultilayer structure of the lower electrode 37, piezoelectric element 38and upper electrode 39 (FIGS. 34B and 35B). The formation of thepiezoelectric element 38 and upper electrode 39 may be implemented as isthe case with the formation of the piezoelectric element 18 and upperelectrode 19 in the aforesaid embodiment.

It is here noted that at this step, the wire 39 a and terminal 39 b (seeFIG. 11) may be formed at the same time, too.

Then, the desired site is removed from another surface of the siliconwafer 1 per segment to form an opening 33, thereby forming a frameportion 32, and a thinner portion 32 a is formed in a part of the sitewhere there are the drive portions 36 positioned, such that it is incontact with the opening 33, whereby a multiplicity of piezoelectricmirror devices 31 are prepared (FIG. 34C).

The formation of the opening 33 and thinner portion 32 a in the siliconwafer 1 may be implemented as is the case with the formation of theopening 13 and thinner portion 12 a in the aforesaid embodiment.

Then, a multiplicity of piezoelectric mirror devices 31 are diced intosuch individual piezoelectric mirror devices 31 as shown in FIGS. 11 and12.

FIGS. 36A, 36B and 36C are step diagrams for a further embodiment of theinventive fabrication process where the piezoelectric mirror device 31shown in FIGS. 11 and 12 are taken as an example.

First of all, a silicone wafer 1 is divided into a multiplicity ofsegments (indicated by 1A in FIG. 36A). On one surface of the siliconwafer 1 per segment, a pair of lower electrodes 37 are provided, and apiezoelectric element 38 and an upper electrode 39 are stacked on thelower electrodes 37 in this order to prepare a pair of drive portions 36that are a multilayer of the lower electrodes 37, piezoelectric element38 and upper electrode 39 (FIG. 36A). The drive portions 36 may beformed as is the case with the drive portions 26 in the aforesaidembodiment.

It is here noted that at this step, the wire 37 a and terminal 37 b, andthe wire 39 a and terminal 39 b (see FIG. 11) may be formed at the sametime, too.

Then, a mirror portion 34 and a pair of mirror support portions 35adapted to support the mirror portion 34 are integrally formed of thematerial having a Young's modulus of up to 160 GPa such that they arepositioned between a pair of drive portions 36 (FIG. 36B). For thematerial having a Young's modulus of up to 160 GPa, the materialsmentioned in the aforesaid embodiment may be used. Further, evenmaterials having a Young's modulus of greater than 160 GPa may be usedin the event that in combination with the electrically conductivematerial(s) having a Young's modulus of up to 160 GPa, they provide amultilayer structure having a Young's modulus of up to 160 GPa. It ishere noted that the piezoelectric element 38 has been formed at theprevious step; there is no special need of taking care of the meltingpoint of the material used with a Young's modulus of up to 160 GPa.

The mirror portion 34 and mirror support portions 35 may be formed as isthe case with the mirror portion 34 and mirror support portions 35 inthe aforesaid embodiment. However, it is noted that the mirror supportportions 35 are formed such that their ends provide positions to whichthe thinner portion 32 a formed later is lockable.

It is noted that when the light reflectance of the material used for themirror portion 34 and the mirror support portions 35 is insufficient, areflective layer comprising a high reflectance material should better beformed on the mirror portion 34. Such a reflective layer may be formedof the same materials as mentioned in the aforesaid embodiment.

Then, the desired site is removed from another surface of the siliconwafer 1 per segment to form an opening 33, thereby forming a frameportion 32, and the thinner portion 32 a is formed in a part of the sitewhere there are the drive portions 36 positioned, such that it is incontact with the opening 33, whereby a multiplicity of piezoelectricmirror devices 31 are prepared (FIG. 36C).

The formation of the opening 33 and thinner portion 32 a in the siliconwafer 1 may be implemented as is the case with the formation of theopening 13 and thinner portion 12 a in the aforesaid embodiment.

Then, a multiplicity of piezoelectric mirror devices 31 are diced intosuch individual piezoelectric mirror devices 31 as shown in FIGS. 11 and12.

(4) FIGS. 37A-37E and FIGS. 38A-38C are step diagrams for a furtherembodiment of the inventive fabrication process where the piezoelectricmirror device 41, 41′ shown in FIGS. 13 to 16 is taken as an example.

First of all, a silicone wafer 1 is divided into a multiplicity ofsegments (indicated by 1A in FIG. 37A). On one surface of the siliconwafer 1 per segment, a pair of lower electrodes 47 are provided, and apiezoelectric element 48 is formed on the lower electrodes 47 (FIGS. 37Aand 38A). The formation of the lower electrodes 47 and piezoelectricelement 48 may be implemented as is the case with the formation of thelower electrodes 27 and piezoelectric element 28 in the aforesaidembodiment.

It is here noted that at this step, the wire 47 a and terminal 47 b (seeFIGS. 13 and 15) may be formed at the same time, too.

Then, a resist layer 3 is formed in such a way as to expose the uppersurface of the piezoelectric element 48 to view, thereby forming a flatsurface (FIGS. 37B and 38B).

Then, the upper electrode 49 positioned on the exposed piezoelectricelement 48, a mirror portion 44 between the upper electrodes 49, and apair of mirror support portions 45 adapted to join the mirror portion 44to the upper electrode 49 are integrally formed of the electricallyconductive material having a Young's modulus of up to 160 PGa, afterwhich an unnecessary portion of the resist layer 3 is removed (FIGS. 37Cand 38C), whereby a pair of drive portions 46 that are a multilayerstructure of the lower electrodes 47, piezoelectric element 48 and upperelectrode 49 are formed, and the mirror portion 44 and mirror supportportions 45 are provided between the drive portions 46. For theelectrically conductive material having a Young's modulus of up to 160GPa, use may be made of those mentioned in the aforesaid embodiment.Such materials may be used alone or in combination of two or moreproviding a multilayer structure. Further, even materials having aYoung's modulus of greater than 160 GPa may be used in the event that incombination with material(s) having a Young's modulus of up to 160 GPa,they provide a multilayer structure having a Young's modulus of up to160 GPa. It is here noted that the piezoelectric element 48 has beenformed at the previous step; there is no special need of taking care ofthe melting point of the material used with a Young's modulus of up to160 GPa.

The integral formation of the mirror portion 44, mirror support portions45 and upper electrode 49 may be implemented as is the case with theformation of the mirror portion 14, mirror support portions 15 and lowerelectrode 17 in the aforesaid embodiment.

It is here noted that at this step, the wire 49 a and terminal 49 b (seeFIGS. 13 and 15) may be formed at the same time, too.

Then, the desired site is removed from another surface of the siliconwafer 1 per segment to form an opening 43, thereby forming a frameportion 42. Here, if a cutout 43 a is formed in a part of the site wherethere are the drive portions 46 positioned, such that it is in contactwith the opening 43, a multiplicity of piezoelectric mirror devices 41are prepared (FIG. 37D), and if a thinner portion 42 a is formed in apart of the site where there are the drive portions 46 positioned, suchthat it is in contact with the opening 43, a multiplicity ofpiezoelectric mirror devices 41′ are prepared (FIG. 37E).

The formation of the opening 43 and cutout 43 a in the silicon wafer 1,and the formation of the opening 43 and thinner portion 42 a in thesilicon wafer 1 may be implemented as is the case with the formation ofthe opening 13 and cutout 13 a, and the opening 13 and thinner portion12 a in the aforesaid embodiment.

Then, a multiplicity of piezoelectric mirror devices 41 are diced intosuch individual piezoelectric mirror devices 41 as shown in FIGS. 13 and14. Likewise, a multiplicity of piezoelectric mirror devices 41′ arediced into such individual piezoelectric mirror devices 41′ as shown inFIGS. 15 and 16.

Such inventive fabrication processes as described above make use ofsilicon wafers, or they dispenses with the use of SOI wafers having asilicon oxide layer, so that fabrication costs can be curtailed.

It is here noted that the above fabrications processes of piezoelectricmirror devices are provided for the purpose of illustration alone, andso the invention is never limited to them.

[Optical Equipment]

The optical equipment according to the invention is now explained.

FIG. 39 is illustrative in construction of the optical equipment of theinvention embodied as an image display such as a display or projector.Referring to FIG. 39, an optical equipment 101 of the inventioncomprises a laser light source 102, a projection screen 103, and anoptical system 105 adapted to guide light leaving the laser light source102 to the projection screen 103. The optical system 105 of this opticalequipment 101 includes a condenser lens group 106, a piezoelectricmirror device 107, and a projector lens group 108, wherein thatpiezoelectric mirror device 107 is defined by the inventivepiezoelectric mirror device. The inventive piezoelectric mirror deviceused here, for instance, may be of the biaxial type wherein uponreflection of incident light from the condenser lens group 106 towardthe projector lens group 108, the X/Y (horizontal/vertical) directionscan be scanned. And by the thus scanned laser light, images can bedisplayed on the projection screen 103 via the projector lens group 108.

It is here noted that the aforesaid optical equipment is given for thepurpose of illustration alone; the invention is never limited to itsembodiment.

The invention is now explained in more details with reference to morespecific examples.

Example 1

A 625-μm thick silicon wafer was divided into a multiplicity of squaresegments, each having one side of 5.5 mm. On one surface of the siliconwafer there was a photosensitive resist (LA900 made by Tokyo Ohka KogyoCo., Ltd.) coated by spin coating, and that resist was exposed to lightvia a mask and then developed to form a segmented resist pattern. A Tithin film (of 30 nm in thickness) having a Young's modulus of 115.7 GPaand an Au thin film (of 1 μm (1,000 nm) in thickness) having a Young'smodulus of 78.0 GPa were coated and stacked by sputtering over thatresist pattern to form an electrode film. This electrode film(multilayer structure) was going to have a calculated Young's modulus of79.1 GPa. Then, AZ Remover manufactured by AZ Electronic Materials Co.,Ltd. was used for the application of ultrasonic waves thereby removingthe aforesaid resist pattern and, at the same time, lifting off theelectrode film on the resist pattern. In this way, a pair of lowerelectrodes, a mirror portion positioned between the lower electrodes anda pair of mirror support portions adapted to join the mirror portion tothe lower electrodes were formed as one integral piece. The thus formedmirror support portions each had a width of 10 μm, and simultaneously atthis step, wires and terminals connected to the lower electrodes wereformed, too.

Then, lead zirconate titanate (PZT) was sputtered on a pair of lowerelectrodes via a mask to form a thin film, and then sintered (at 600° C.for 120 minutes) to prepare a piezoelectric element (of 10 μm inthickness).

Then, a photosensitive resist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.)was spin coated on the silicon wafer with the piezoelectric element thusformed on it, exposed to light via a mask, and then developed to form aresist pattern for upper electrode formation. A Cr thin film (of 50 nmin thickness) and an Au thin film (of 300 nm in thickness) were coatedand stacked by sputtering over that resist pattern to form an electrodefilm. Then, AZ Remover manufactured by AZ Electronic Materials Co., Ltd.was used for the application of ultrasonic waves thereby removing theaforesaid resist pattern and, at the same time, lifting off theelectrode film on the resist pattern. In this way, a pair of upperelectrodes were formed on the aforesaid piezoelectric element.Simultaneously at this step, wires and terminals connected to the upperelectrodes were formed, too.

Thus, a drive portion built up of a multilayer structure comprising thelower electrodes, piezoelectric element and upper electrodes was formed.

Then, on another surface of the silicon wafer there was a photosensitiveresist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.) spin coated, which wasin turn exposed to light via a mask and then developed to form a resistpattern for the formation of an opening and a cutout. Then, this resistpattern was used as a mask to implement DRIE (deep reactive ionetching), whereby at a site where there were the lower electrodes, theyacted as an etching stopper thereby forming the cutout, and at anothersite, a through-hole was formed through the silicon wafer therebyforming the opening. In this way, a multiplicity of piezoelectric mirrordevices were prepared.

Finally, the aforesaid multiplicity of piezoelectric mirror devices werediced into such individual piezoelectric mirror devices as shown inFIGS. 1, 2 and 3.

Example 2

A 625-μm thick silicon wafer was divided into a multiplicity of squaresegments, each having one side of 5.5 mm. On one surface of the siliconwafer there was a photosensitive resist (LA900 made by Tokyo Ohka KogyoCo., Ltd.) coated by spin coating, and that resist was exposed to lightvia a mask and then developed to form a segmented resist pattern forlower electrodes. A Ti thin film (of 50 nm in thickness) and a Pt thinfilm (of 300 nm in thickness) were stacked by sputtering over thatresist pattern to form an electrode film. Then, AZ Remover manufacturedby AZ Electronic Materials Co., Ltd. was used for the application ofultrasonic waves thereby removing the aforesaid resist pattern and, atthe same time, lifting off the electrode film on the resist pattern. Inthis way, a pair of lower electrodes were formed, and simultaneously atthis step, wires and terminals connected to the lower electrodes wereformed, too.

Then, lead zirconate titanate (PZT) was sputtered on a pair of lowerelectrodes via a mask to form a thin film, and then sintered (at 600° C.for 120 minutes) to prepare a piezoelectric element (of 10 μm inthickness). Note here that the piezoelectric element was formed suchthat one of the lower electrodes had a smaller area than that of anotherlower electrode so that it was exposed 1,000 μm in the direction ofanother.

Then, a photosensitive resist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.)was spin coated on the silicon wafer with the piezoelectric element thusformed on it, exposed to light via a mask, and then developed to form aresist pattern for upper electrode formation. A Cr thin film (of 50 nmin thickness) and an Au thin film (of 300 nm in thickness) were stackedby sputtering over that resist pattern to form an electrode film. Then,AZ Remover manufactured by AZ Electronic Materials Co., Ltd. was usedfor the application of ultrasonic waves thereby removing the aforesaidresist pattern and, at the same time, lifting off the electrode film onthe resist pattern. In this way, there were a pair of upper electrodesformed on the aforesaid piezoelectric element. Simultaneously at thisstep, wires and terminals connected to the upper electrodes were formed,too.

Thus, a drive portion built up of a multilayer structure comprising thelower electrodes, piezoelectric element and upper electrodes was formed.

Then, on the silicon wafer with a pair of drive portions formed on it,there was a photosensitive resist (LA900 made by Tokyo Ohka Kogyo Co.,Ltd.) spin coated, which was in turn exposed to light and then developedto form a resist pattern for the formation of a mirror portion andmirror support portions. A Ti thin film (of 30 nm in thickness) having aYoung's modulus of 115.7 GPa and an Au thin film (of 1 μm (1,000 nm))having a Young's modulus of 78.0 GPa were coated and stacked bysputtering over that resist pattern to form a thin film. This thin film(multilayer structure) was going to have a calculated Young's modulus of79.1. Then, AZ Remover manufactured by AZ electronic Materials Co., Ltd.was used for the application of ultrasonic waves thereby removing theaforesaid resist pattern and, at the same time, lifting off the thinfilm on the resist pattern. In this way, a mirror portion positionedbetween a pair of drive portions and a pair of mirror support portionsadapted to join the mirror portion to the lower electrodes were formedas an integral piece. The thus formed mirror support portions each had awidth of 10 μm.

Then, on another surface of the silicon wafer there was a photosensitiveresist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.) spin coated, which wasin turn exposed to light via a mask and then developed to form a resistpattern for the formation of an opening. Then, this resist pattern wasused as a mask to implement DRIE (deep reactive ion etching) down to adepth of 605 μm. Then, the aforesaid resist pattern was removed, and thephotosensitive resist was again spin coated, exposed to light via a maskand thereafter developed to form a resist pattern for the formation ofan opening and a thinner portion. Then, DRIE (deep reactive ion etching)was implemented with that resist patter used as a mask, until theopening was formed, whereby there was a 20-μm thick thinner portionformed at a site where there were the lower electrodes. In this way, amultiplicity of piezoelectric mirror devices were prepared.

Finally, the aforesaid multiplicity of piezoelectric mirror devices werediced into such individual piezoelectric mirror devices as shown inFIGS. 9 and 10.

Example 3

A 625-μm thick silicon wafer was divided into a multiplicity of squaresegments, each having one side of 5.5 mm. On one surface of the siliconwafer there was a photosensitive resist (LA900 made by Tokyo Ohka KogyoCo., Ltd.) coated by spin coating, and that resist was exposed to lightvia a mask and then developed to form a segmented resist pattern. A Tithin film (of 30 nm in thickness) having a Young's modulus of 115.7 GPaand an Au thin film (of 1 μm (1,000 nm) in thickness) having a Young'smodulus of 78.0 GPa were coated and stacked by sputtering over thatresist pattern to form an electrode film. This electrode film was goingto have a calculated Young's modulus of 79.1. Then, AZ Removermanufactured by AZ Electronic Materials Co., Ltd. was used for theapplication of ultrasonic waves thereby removing the aforesaid resistpattern and, at the same time, lifting off the electrode film on theresist pattern. In this way, a pair of lower electrodes, a mirrorportion positioned between the lower electrodes and a pair of mirrorsupport portions joined to the mirror portion were formed. The thusformed mirror support portions each had a width of 10 mm with a distanceof 500 mm between the ends of the mirror support portions and the lowerelectrodes, and simultaneously at this step, wires and terminalsconnected to the lower electrodes were formed, too.

Then, lead zirconate titanate (PZT) was sputtered on a pair of lowerelectrodes via a mask to form a thin film, and then sintered (at 600° C.for 120 minutes) to prepare a piezoelectric element (of 10 μm inthickness).

Then, a photosensitive resist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.)was spin coated on the silicon wafer with the piezoelectric element thusformed on it, exposed to light via a mask, and then developed to form aresist pattern for upper electrode formation. A Cr thin film (of 50 nmin thickness) and an Au thin film (of 300 nm in thickness) were coatedand stacked by sputtering over that resist pattern to form an electrodefilm. Then, AZ Remover manufactured by AZ Electronic Materials Co., Ltd.was used for the application of ultrasonic waves thereby removing theaforesaid resist pattern and, at the same time, lifting off theelectrode film on the resist pattern. In this way, there were a pair ofupper electrodes formed on the aforesaid piezoelectric element.Simultaneously at this step, wires and terminals connected to the upperelectrodes were formed, too.

Thus, a drive portion built up of a multilayer structure comprising thelower electrodes, piezoelectric element and upper electrodes was formed.

Then, on another surface of the silicon wafer there was a photosensitiveresist (LA900 made by Tokyo Ohka

Kogyo Co., Ltd.) spin coated, which was in turn exposed to light via amask and then developed to form a resist pattern for the formation of anopening. Then, this resist pattern was used as a mask to implement DRIE(deep reactive ion etching) down to a depth of 605 μm. Then, theaforesaid resist pattern was removed, and the photosensitive resist wasagain spin coated, exposed to light via a mask and thereafter developedto form a resist pattern for the formation of an opening and a thinnerportion. Then, DRIE (deep reactive ion etching) was implemented withthat resist patter used as a mask, until the opening was formed, wherebythere was a 20-μm thick thinner portion formed at a site where therewere the lower electrodes and at an area from the ends of the mirrorsupport portions to 1,000 mm in a direction toward the mirror portion,and the opening was provided between the mirror support portions and themirror portion while the ends of the mirror support portions were lockedto that thinner portion. In this way, a multiplicity of piezoelectricmirror devices were prepared.

Finally, the aforesaid multiplicity of piezoelectric mirror devices werediced into such individual piezoelectric mirror devices as shown inFIGS. 11 and 12.

Example 4

A 625-μm thick silicon wafer was divided into a multiplicity of squaresegments, each having one side of 5.5 mm. On one surface of the siliconwafer there was a photosensitive resist (LA900 made by Tokyo Ohka KogyoCo., Ltd.) coated by spin coating, and that resist was exposed to lightvia a mask and then developed to form a segmented resist pattern forlower electrode formation. A Ti thin film (of 30 nm in thickness) and aPt thin film (of 300 nm in thickness) were coated and stacked bysputtering over that resist pattern to form an electrode film. Then, AZRemover manufactured by AZ Electronic Materials Co., Ltd. was used forthe application of ultrasonic waves thereby removing the aforesaidresist pattern and, at the same time, lifting off the electrode film onthe resist pattern. In this way, a pair of lower electrodes were formed,and simultaneously at this step, wires and terminals connected to thelower electrodes were formed, too.

Then, lead zirconate titanate (PZT) was sputtered on a pair of lowerelectrodes via a mask to form a film, and then sintered (at 600° C. for120 minutes) to prepare a piezoelectric element (of 10 μm in thickness).

Then, a positive type photosensitive resist (AZ5218 manufactured by AZElectronic Materials Co., Ltd.) was spin coated on the silicon waferwith the lower electrodes and piezoelectric element thus formed on it,and areas except between the piezoelectric elements were exposed tolight, and then developed to expose the surfaces of the piezoelectricelements and make the piezoelectric elements and a site between themflat. Then, a photosensitive resistive (LA900 made by Tokyo Ohka KogyoCo., Ltd.) was spin coated, exposed to light and then developed to forma resist pattern. A Ti thin film (50 nm in thickness) having a Young'smodulus of 115.7 GPa and an Au thin film (of 5 μm (5,000 nm) inthickness) having a Young's modulus of 78.0 GPa were coated and stackedby sputtering on that resist pattern to form an electrode film. Thiselectrode film (multilayer structure) was going to have a calculatedYoung's modulus of 78.4 GPa. Then, AZ Remover manufactured by AZElectronic Materials Co., Ltd. was used for the application ofultrasonic waves thereby removing all the aforesaid resist patterns and,at the same time, lifting off the electrode film on the resist pattern,whereby a pair of upper electrodes positioned on the piezoelectricelement, a mirror portion positioned between the upper electrodes and apair of mirror support portions adapted to join the mirror portion tothe upper electrodes were formed as one integral piece. Thus, a driveportion built up of a multilayer structure comprising the lowerelectrodes, piezoelectric element and upper electrodes was formed, andthe mirror support portions each had a width of 10 μm. Note here thatsimultaneously at this step, wires and terminals connected to the upperelectrodes were formed, too.

Then, on another surface of the silicon wafer there was a photosensitiveresist (LA900 made by Tokyo Ohka Kogyo Co., Ltd.) spin coated, which wasin turn exposed to light via a mask and then developed to form a resistpattern for the formation of an opening and a cutout. Then, this resistpattern was used as a mask to implement DRIE (deep reactive ionetching), whereby at a site where there were the lower electrodes, theyacted as an etching stopper thereby forming the cutout, and at anothersite, a through-hole was formed through the silicon wafer therebyforming the opening. In this way, a multiplicity of piezoelectric mirrordevices were prepared.

Finally, the aforesaid multiplicity of piezoelectric mirror devices werediced into such individual piezoelectric mirror devices as shown inFIGS. 13 and 14.

Example 5

Such individual piezoelectric mirror devices as shown in FIGS. 1, 2 and3 were obtained following Example 1 with the exception that a Ti thinfilm (of 200 nm in thickness) having a Young's modulus of 115.7 GPa andan Au thin film (of 1 μm (1,000 nm) in thickness) having a Young'smodulus of 78.0 GPa were stacked together by sputtering into anelectrode film. The electrode film (multilayer structure) here had acalculated Young's modulus of 84.2.

Example 6

Such individual piezoelectric mirror devices as shown in FIGS. 1, 2 and3 were obtained following Example 1 with the exception that an Au thinfilm (of 1 μm (1,000 nm) in thickness) having a Young's modulus of 78.0GPa was formed by sputtering into an electrode film.

Example 7

Such individual piezoelectric mirror devices as shown in FIGS. 1, 2 and3 were obtained following Example 1 with the exception that a Ti thinfilm (of 400 nm in thickness) having a Young's modulus of 115.7 GPa anda Pt thin film (of 1 μm (1,000 nm) in thickness) having a Young'smodulus of 168 GPa were stacked together by sputtering into an electrodefilm. The electrode film (multilayer structure) here had a calculatedYoung's modulus of 152.9.

Example 8

Such individual piezoelectric mirror devices as shown in FIGS. 1, 2 and3 were obtained following Example 1 with the exception that a Cu thinfilm (of 2 μm (2,000 nm) in thickness) having a Young's modulus of 130GPa was formed by sputtering into an electrode film.

Example 9

Such individual piezoelectric mirror devices as shown in FIGS. 1, 2 and3 were obtained following Example 1 with the exception that an Au thinfilm (of 1 μm (1,000 nm) in thickness) having a Young's modulus of 82.7GPa was formed by sputtering into an electrode film.

Comparative Example

Piezoelectric mirror devices were obtained following Example 2 with theexception that a mirror portion and mirror support portions were formedof Si having a Young's modulus of 166.0 GPa.

[Estimations]

With the respective piezoelectric mirror devices of Examples 1-9 and thecomparative example, ac voltage (±25 V, 50 Hz) was applied to the upperelectrodes under the following conditions while the lower electrodeswere at a GND potential to measure the angles of deviation of the mirrorportions. The results are tabulated in Table 1 given below.

TABLE 1 Mirror Support Portions Young's Modulus of the Multi-layerPiezo- Structure electric Young's (Calculated Mirror Modulus ThicknessValues) Angle of Device Material (GPa) (nm) (GPa) Deviation Ex. 1 Ti 115 30  79.1 ±20~25 Au 78 1000 Ex. 2 Ti 115  30  79.1 ±20~25 Au 78 1000 Ex.3 Ti 115  30  79.1 ±20~25 Au 78 1000 Ex. 4 Ti 115  50  78.4 ±20~25 Au 785000 Ex. 5 Ti 115  200  84.2 ±20~25 Au 78 1000 Ex. 6 Au 78 1000 — ±20~25Ex. 7 Ti 115  400 152.9 ±15~20 Pt 168 1000 Ex. 8 Cu 130 2000 — ±17~25Ex. 9 Ag 82.7 1000 — ±20~25 Comp. Ex. Si 166 1000 —  ±7~10

As can be seen from Table 1, the angles of deviation of the mirrorportions of the respective piezoelectric mirror devices according toExamples 1 to 9 were much larger than that of the mirror portion of thecomparative piezoelectric mirror device.

INDUSTRIAL APPLICABILITY

The invention is applicable to the fabrication or the like ofpiezoelectric mirror devices making use of a piezoelectric element fordriving mirror portions.

1. A piezoelectric mirror device fabrication process, comprising: a stepof dividing a silicon wafer into a multiplicity of segments, wherein onone surface of said silicon wafer per segment, a pair of lowerelectrodes, a mirror portion positioned between said lower electrodesand a pair of mirror support portions adapted to join said mirrorportion to said lower electrodes are formed of an electricallyconductive material having a Young's modulus of up to 160 GPa and amelting point higher than that of a piezoelectric element to be formedlater, a step of stacking the piezoelectric element and an upperelectrode on said lower electrodes in this order to prepare a pair ofdrive portions that are a multilayer structure of the lower electrodes,the piezoelectric element and the upper electrode, a step of removingthe silicon wafer in a desired pattern from another surface of saidsilicon wafer per segment to form an opening thereby preparing a frameportion, wherein said mirror portion is rotatably supported by saidmirror support portions at said opening, and at a part of a site of saidframe portion where there are said drive portions positioned, a cutoutor thinner portion is formed in contact with said opening to obtain amultiplicity of piezoelectric mirror devices, and a step of dicing saidmultiplicity of piezoelectric mirror devices into individual ones.
 2. Apiezoelectric mirror device fabrication process, comprising: a step ofdividing a silicon wafer into a multiplicity of segments, wherein on onesurface of said silicon wafer per segment, a pair of lower electrodes, apiezoelectric element on said lower electrodes and an upper electrodeare stacked in this order to prepare a pair of drive portions that are amultilayer structure of the lower electrodes, the piezoelectric elementand the upper electrode, a step of forming a mirror portion positionedbetween said drive portions and a pair of mirror support portionsextending from said mirror portion toward said drive portions of amaterial having a Young's modulus of up to 160 GPa such that said mirrorsupport portions are locked at ends to the lower electrodes constitutinga part of said drive portions, a step of removing the silicon wafer in adesired pattern from another surface of said silicon wafer per segmentto form an opening thereby preparing a frame portion, wherein saidmirror portion is rotatably supported by said mirror support portions atsaid opening, and at a part of a site of said frame portion where thereare said drive portions positioned, a cutout or thinner portion isformed in contact with said opening to obtain a multiplicity ofpiezoelectric mirror devices, and a step of dicing said multiplicity ofpiezoelectric mirror devices into individual ones.
 3. A piezoelectricmirror device fabrication process, comprising: a step of dividing asilicon wafer into a multiplicity of segments, wherein on one surface ofsaid silicon wafer per segment, a pair of lower electrodes, a mirrorportion positioned between said lower electrodes and a pair of mirrorsupport portions extending from said mirror portion down toward saidlower electrodes are formed of an electrically conductive materialhaving a Young's modulus of up to 160 GPa and a melting point higherthan that of a piezoelectric element to be formed later, a step ofstacking the piezoelectric element and an upper electrode on said lowerelectrodes in this order to prepare a pair of drive portions that are amultilayer structure of the lower electrodes, the piezoelectric elementand the upper electrode, a step of removing the silicon wafer in adesired pattern from another surface of said silicon wafer per segmentto form an opening thereby preparing a frame portion, wherein saidmirror portion is rotatably supported by said mirror support portions atsaid opening, and at a part of a site of said frame portion where thereare said drive portions positioned, a thinner portion is formed in sucha way as to be in contact with said opening and lock ends of said mirrorsupport portions to obtain a multiplicity of piezoelectric mirrordevices, and a step of dicing said multiplicity of piezoelectric mirrordevices into individual ones.
 4. A piezoelectric mirror devicefabrication process, comprising: a step of dividing a silicon wafer intoa multiplicity of segments, wherein on one surface of said silicon waferper segment, a pair of lower electrodes, a piezoelectric element on saidlower electrodes and an upper electrodes are stacked together in thisorder to prepare a pair of drive portions that are a multilayerstructure of the lower electrodes, the piezoelectric element and theupper electrode, a step of forming a mirror portion positioned betweensaid drive portions and a pair of mirror support portions extending fromsaid mirror portion toward said drive portions of a material having aYoung's modulus of up to 160 GPa, a step of removing the silicon waferin a desired pattern from another surface of said silicon wafer persegment to form an opening thereby preparing a frame portion, whereinsaid mirror portion is rotatably supported by said mirror supportportions at said opening, and at a part of a site of said frame portionwhere there are said drive portions positioned, a thinner portion isformed in such a way as to be in contact with said opening and lock endsof said mirror support portions to obtain a multiplicity ofpiezoelectric mirror devices, and a step of dicing said multiplicity ofpiezoelectric mirror devices into individual ones.
 5. A piezoelectricmirror device fabrication process, comprising: a step of dividing asilicon wafer into a multiplicity of segments, wherein on one surface ofsaid silicon wafer per segment, a pair of lower electrodes and apiezoelectric element on said lower electrodes are formed, a step offorming a resist layer such that a surface of said piezoelectric elementis exposed and making said resist layer flat, then forming an upperelectrode positioned on said piezoelectric element, a mirror portionpositioned halfway between said piezoelectric elements and a pair ofmirror support portions adapted to join said mirror portion to saidupper electrode of an electrically conductive material having a Young'smodulus of up to 160 GPa to prepare a pair of drive portions that are amultilayer structure of the lower electrodes, the piezoelectric elementand the upper electrode, and then removing said resist, a step ofremoving the silicon wafer in a desired pattern from another surface ofsaid silicon wafer per segment to form an opening thereby preparing aframe portion, wherein said mirror portion is rotatably supported bysaid mirror support portions at said opening, and at a part of a site ofsaid frame portion where there are said drive portions positioned, acutout or thinner portion is formed in contact with said opening toobtain a multiplicity of piezoelectric mirror devices, and a step ofdicing said multiplicity of piezoelectric mirror devices into individualones.